REST API: Validate post format support in WP_REST_Posts_Controller

[yogeshbhutkar]

Description:

Implement a validation check to ensure the given post type supports post formats before serving the data through the REST API.

Trac ticket: https://core.trac.wordpress.org/ticket/62646

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Props yogeshbhutkar, peterwilsoncc.

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[github-actions]

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[peterwilsoncc]

Thanks @yogeshbhutkar, this looks good to me.

I took the liberty of pushing a test to your pull request and running them against the unmodified code to demonstrate the failure.

With your changes, the tests pass as expected.

I've also merged in trunk to ensure the PR can be committed without any conflicts.

[peterwilsoncc]

Merged in r59544 / 7381a82

Thank you!