SerializedFile metadata command (Unity version, platform and typetree info)

[SkowronskiAndrew]

Summary

This branch adds a new serialized-file metadata command and expands the depth of metadata parsing in the
UnityDataTool.

New serialized-file metadata Command

A new subcommand that exposes the full metadata section of a Unity serialized file, including:

• File format version and target platform
• Whether the file uses type trees
• Type tree data — the full type tree table with type hashes, script type information, and per-type node structure
• Object list — parsed directly from the metadata section, fixing an existing bug where object listing failed on files
  without type trees
• External file references — the list of external files referenced by the serialized file
• Script types table — the final piece of the metadata section, now fully parsed

Note: i keep this information separate from "header". One reason is to match how it is actually structured inside SerializedFiles. Another reason is to keep the header command very light weight because we use to check each file before trying to open it. The meta-data command will potentially pull a lot more data.

Note: In this case the Json and text output for the command diverge. I hope this isn't confusing. But it seemed reasonable to keep the text version short and to the point rather than try to express complex arrays in text formats. The json format is more appropriate for the detailed structured representation of the metadata.

Refactoring & Code Quality

• File utility helpers (ArchiveDetector, GuidHelper, BinaryFileHelper) moved from the Analyzer project into a new
  dedicated UnityBinaryFormat assembly, making them cleaner to reuse across tools
• Better error reporting with more descriptive messages (e.g. when passing the wrong file, or files without typetrees to the dump, archive, analyze or serialized-file commands)
• Guards use to avoid attempting to parse files from future/unknown format versions.

Test Coverage

• New test cases for the new information in the metadata command
• Additional reference binary files added (including Addressable build variants) to broaden test coverage, including the recent changes to the file format for typetree extraction support.
• I also did a fair bit of manual testing of the reference files and other projects to check if the output and errorhandling worked well.

Documentation

New subcommand is documented, which also helps explain some of the concepts in these data structures.

[Copilot]

Pull request overview

Adds richer SerializedFile metadata parsing (including TypeTree entry headers for v19–v23) and exposes it via a new serialized-file metadata / sf metadata CLI subcommand, along with test fixtures and NUnit coverage for common TypeTree configurations (inline, extracted, disabled, SerializeReference types).

Changes:

• Introduces BinaryFileHelper / UnityHash128 and extends SerializedFileDetector.TryParseMetadata to parse TypeTree section counts and per-entry metadata for regular and SerializeReference type lists.
• Adds sf metadata command with text + JSON output (including TypeTree arrays in JSON).
• Adds/updates test data and NUnit tests for metadata parsing and new CLI behavior.

Reviewed changes

Copilot reviewed 8 out of 24 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
UnityDataTool/SerializedFileCommands.cs	Adds HandleMetadata plus text/JSON output helpers for new metadata command.
UnityDataTool/Program.cs	Registers new serialized-file metadata subcommand (alias sf metadata).
UnityDataTool.Tests/SerializedFileCommandTests.cs	Adds initial CLI test coverage for metadata command error path (legacy version).
Analyzer/Util/SerializedFileDetector.cs	Adds SerializedFileMetadata / TypeTreeInfo models and implements TypeTree metadata parsing in TryParseMetadata.
Analyzer/Util/BinaryFileHelper.cs	Adds shared endian-aware binary helpers and UnityHash128.
Analyzer.Tests/FileDetectionTests.cs	Adds NUnit tests validating metadata parsing across representative files; adjusts one archive test path.
Documentation/command-serialized-file.md	Documents new metadata subcommand under serialized-file.
TestCommon/Data/LegacyFormats/v22_strippedVersion	Adds stripped-version serialized file fixture for metadata parsing scenarios.
TestCommon/Data/AssetBundleTypeTreeVariations/README.md	Documents the new typetree-variation fixtures and how to inspect them.
TestCommon/Data/AssetBundleTypeTreeVariations/v23_extracted/prefab_with_serializedreference.serializedfile	Fixture: v23 extracted typetree prefab serializedfile.
TestCommon/Data/AssetBundleTypeTreeVariations/v23_extracted/packedassets_assets_all.bundle	Fixture: v23 extracted typetree main bundle.
TestCommon/Data/AssetBundleTypeTreeVariations/v23_extracted/monoscriptbundle.serializedfile	Fixture: v23 extracted typetree monoscript bundle serializedfile.
TestCommon/Data/AssetBundleTypeTreeVariations/v23_extracted/MonoScript_monoscripts_dde848dc9848681e340a8b4fa9bd7578.bundle	Fixture: v23 extracted typetree autoscript bundle.
TestCommon/Data/AssetBundleTypeTreeVariations/v23_extracted/AssetBundle.typetreedata	Fixture: extracted typetree store archive used by v23 extracted builds.
TestCommon/Data/AssetBundleTypeTreeVariations/v23_Inline/prefab_with_serializedreference.serializedfile	Fixture: v23 inline typetree prefab serializedfile.
TestCommon/Data/AssetBundleTypeTreeVariations/v23_Inline/packedassets_assets_all.bundle	Fixture: v23 inline typetree main bundle.
TestCommon/Data/AssetBundleTypeTreeVariations/v23_Inline/monoscriptbundle.serializedfile	Fixture: v23 inline typetree monoscript bundle serializedfile.
TestCommon/Data/AssetBundleTypeTreeVariations/v23_Inline/MonoScript_monoscripts_dde848dc9848681e340a8b4fa9bd7578.bundle	Fixture: v23 inline typetree autoscript bundle.
TestCommon/Data/AssetBundleTypeTreeVariations/v22/prefab_with_serializedreference.serializedfile	Fixture: v22 typetree prefab serializedfile (SerializeReference).
TestCommon/Data/AssetBundleTypeTreeVariations/v22/packedassets_assets_all.bundle	Fixture: v22 typetree main bundle.
TestCommon/Data/AssetBundleTypeTreeVariations/v22/monoscriptbundle.serializedfile	Fixture: v22 typetree monoscript bundle serializedfile.
TestCommon/Data/AssetBundleTypeTreeVariations/v22/MonoScript_monoscripts_dde848dc9848681e340a8b4fa9bd7578.bundle	Fixture: v22 typetree autoscript bundle.

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