Add local version of wp-env schema to .wp-env.json

[t-hamano]

Similar to #61312

What?

This PR adds a reference to the local schema in the wp-env config file used by the Gutenberg project.

Why?

• This will prevent incorrect fields from being defined in future updates to .wp-env.json.
• As mentioned in this comment, there are some fields missing in the current schema. When fixing these, it will be easier to test using the .wp-env.json in the Gutenberg project.

Testing Instructions

• Check out this PR.
• Open the .wp-env.json file in a code editor.
• The code editor should help you auto-complete fields and warn you about invalid fields and values.

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Co-authored-by: t-hamano <wildworks@git.wordpress.org>
Co-authored-by: fabiankaegy <fabiankaegy@git.wordpress.org>
Co-authored-by: ajlende <ajlende@git.wordpress.org>

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[fabiankaegy]

Thanks for adding this 👍

[ajlende]

Looks good!

For our blocks and themes, we test the files with Ajv as part of the automated testing.

gutenberg/test/integration/blocks-schema.test.js

Lines 33 to 42 in ed018ef

	test.each( jsonFiles )( 'validates schema for `%s`', ( filepath ) => {
	// We want to validate the block.json file using the local schema.
	const { $schema, ...blockMetadata } = require( filepath );
	expect( $schema ).toBe( 'https://schemas.wp.org/trunk/block.json' );
	const result = ajv.validate( blockSchema, blockMetadata ) || ajv.errors;
	expect( result ).toBe( true );
	} );

gutenberg/test/integration/theme-schema.test.js

Lines 37 to 47 in ed018ef

	test.each( jsonFiles )( 'validates schema for `%s`', ( filepath ) => {
	// We want to validate the theme.json file using the local schema.
	const { $schema, ...metadata } = require( filepath );
	// we expect the $schema property to be present in the theme.json file
	expect( $schema ).toBeTruthy();
	const result = ajv.validate( themeSchema, metadata ) || ajv.errors;
	expect( result ).toBe( true );
	} );

Adding tests for our .wp-env.json would be a good next step.