Support filtering Instant Results args schema.

[JakePT]

Description of the Change

Adds ep_instant_results_args_schema filter for filtering Instant Results arguments schema.

Closes #3385

How to test the Change

Adding this code should change the default sorting of results.

add_filter(
	'ep_instant_results_args_schema',
	function( $args_schema ) {
		$args_schema['orderby']['default'] = 'date';

		return $args_schema;
	}
);

Changelog Entry

Added - ep_instant_results_args_schema filter for filtering Instant Results arguments schema.> Changed - Existing functionality.

Credits

Props @JakePT

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.