refactor(oas31): use system.fn as source of truth for all components

[pplr]

Changes introduced by the commit b017858 on the Models wrapper should also apply to the Model wrapper.

Motivation and Context

The isExpandable and getProperties injected in the schema context are not the ones from the system.fn context. Overriding these functions in a plugin has a non consistent effect. The overrided functions are used on the Models compoments tree, but not on the Model component.

How Has This Been Tested?

No specific test as been added because this is a refactoring. I executed npm run test.

Checklist

My PR contains...

• No code changes (src/ is unmodified: changes to documentation, CI, metadata, etc.)
• Dependency changes (any modification to dependencies in package.json)
• Bug fixes (non-breaking change which fixes an issue)
• Improvements (misc. changes to existing features)
• Features (non-breaking change which adds functionality)

My changes...

• are breaking changes to a public API (config options, System API, major UI change, etc).
• are breaking changes to a private API (Redux, component props, utility functions, etc.).
• are breaking changes to a developer API (npm script behavior changes, new dev system dependencies, etc).
• are not breaking changes.

Documentation

• My changes do not require a change to the project documentation.
• My changes require a change to the project documentation.
• If yes to above: I have updated the documentation accordingly.

Automated tests

• My changes can not or do not need to be tested.
• My changes can and should be tested by unit and/or integration tests.
• If yes to above: I have added tests to cover my changes.
• If yes to above: I have taken care to cover edge cases in my tests.
• All new and existing tests passed.

[char0n]

LGTM. Thanks for change! At this point it's more a fix than a refactor.