Move deprecated schema markers to JSON ingestion

[jwils]

Summary

• Move deleted_type, deleted_field, and renamed_from from core schema definition into the JSON ingestion schema definition extension.
• Move the deprecated element value object and metadata state into elasticgraph-json_ingestion.
• Keep the existing deprecation-marker docs with the extension APIs that now own the behavior.

Validation

• script/lint
• script/type_check
• script/run_gem_specs elasticgraph-json_ingestion
• bundle exec rspec elasticgraph-schema_definition/spec/unit/elastic_graph/schema_definition/factory_spec.rb

Note: script/run_gem_specs elasticgraph-schema_definition was not run to completion locally because the test datastore was not running (http://localhost:9234).