fix(python): respect FieldMetadata aliases when using model_validate with Pydantic v2

[kafkas]

Description

Adds UncheckedBaseModel.model_validate to de-alias the input object with convert_and_respect_annotation_metadata before passing it to Pydantic, so JSON keys defined via FieldMetadata(alias=...) map to their Python attributes as expected.

Changes Made

• Added the model_validate method to UncheckedBaseModel

Testing

• Unit tests added/updated
• Manual testing completed

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Note

Override UncheckedBaseModel.model_validate (Pydantic v2) to de-alias input via convert_and_respect_annotation_metadata before validation.

• Python core utilities:
  • UncheckedBaseModel (Pydantic v2):
    • Add model_validate override to pre-process inputs with convert_and_respect_annotation_metadata (respects FieldMetadata aliases) before delegating to Pydantic.
  • Serialization:
    • Import convert_and_respect_annotation_metadata alongside get_field_to_alias_mapping.

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