feat: add flexible dependency source resolution

[suxiaogang223]

Purpose

Linked issue: close #103

This PR introduces a flexible dependency source resolution interface for selected third-party dependencies.

It adds:

• PAIMON_DEPENDENCY_SOURCE=AUTO|BUNDLED|SYSTEM
• per-dependency *_SOURCE overrides
• PAIMON_PACKAGE_PREFIX
• compatibility FindXxxAlt.cmake modules
• a centralized dependency resolution summary
• target-based include propagation cleanup for ORC/Avro format targets

Package-manager-specific modes are intentionally left out of this first PR and should be discussed separately.

Tests

Fedora:

• cmake -S . -B build-scope-bundled -DPAIMON_DEPENDENCY_SOURCE=BUNDLED
• cmake --build build-scope-bundled -j$(nproc)
• cmake -S . -B build-scope-auto -DPAIMON_DEPENDENCY_SOURCE=AUTO
• cmake --build build-scope-auto -j$(nproc)
• cmake -S . -B build-scope-tests -DPAIMON_DEPENDENCY_SOURCE=BUNDLED -DPAIMON_BUILD_TESTS=ON
• cmake --build build-scope-tests --target paimon-tests -j$(nproc)

Also verified invalid dependency source values are rejected by configure-time validation.

API and Format

No storage format or public C++ API changes.

Documentation

Updated README and building docs for dependency source configuration.

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[suxiaogang223]

@zjw1111 Hi, could you help review this PR when you have time?

This PR now focuses on flexible dependency source resolution and the sanitizer CI issue has been fixed in the latest commit. The remaining follow-up work and broader design discussion will be tracked in #260, so we can keep this PR scoped and easier to review.

Thanks.🤓