[ASV] Support for reusable pathItems definitions in components

[nilesh25890]

1. A new components.pathItems section was introduced, enabling the definition of reusable pathItems objects.
2. These reusable PathItem objects can be referenced via $ref under specific paths in the paths object, improving reusability and reducing duplication.
3. Inline definitions are still supported: You can define PathItem objects directly under paths, just like in OpenAPI 3.0, without using $ref.
4. "pathItems" is neither schema nor reference object, so any other properties specified along with $ref to pathItems shall be ignored.

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test data.zip

[Maryna-Ko]

Comparing OAS3.0-3.1 should be in scope of implementation\testing due to description #334