Allow classic scripts to depend on modules

[sirreal]

This change proposes allowing a module dependencies to classic scripts.

Classic scripts can add module dependencies like array( 'type' => 'module', 'id' => 'example-module-id' ), where classic script dependencies are simple strings, e.g. 'wp-i18n'.

In order for a classic script to have access to a script module, the script module must appear in the importmap so that it can be accessed by its module identifier from the classic script in a dynamic import.

For a classic script to depend on a module, it must declare that dependency and must be enqueued before the importmap is printed. When the script modules import map is printed, it inspects enqueued scripts to search for module dependencies and includes those dependencies in the import map. Import maps must be printed before any modulepreloads or any script module tags, and only one can be printed (although the specification has changed to allow multiple import maps).

The implementation overrides the WP_Dependencies::add method in WP_Scripts. add is is the main method that handles script registration.
The subclassed implementation is used to partition the provided dependencies array into classic script dependencies and script module dependencies.
The classic script dependencies are passed on to WP_Dependencies::add along with the rest of the arguments. The module dependencies are attached to
the script as extra data module_deps.

When the script modules importmap is printed, it scans through the registered classic scripts for enqueued scripts with module_deps and adds those
modules to the import map.

Script modules in the import map will be available for classic scripts to use via dynamic import().

The dependencies look like this:

wp_register_script_module( '@example/module', /*…*/ );
wp_enqueue_script(
	'example-classic',
	'/classic.js',

	// Dependencies array:
	array(
		// Classic script dependency, no changes.
		'classic-script-dependency',

		// Script module dependency, this form is new.
		array(
			'type' => 'module',
			'id' => '@example/module',
		),
	),
);

Builds on #8009. The implementation here is now independent.

Trac ticket: https://core.trac.wordpress.org/ticket/61500

---

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[github-actions]

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[sirreal]

Is it sufficient to just check enqueued?

Suggested change

	if (
	! $wp_scripts->query( $handle, 'done' ) &&
	! $wp_scripts->query( $handle, 'to_do' ) &&
	! $wp_scripts->query( $handle, 'enqueued' )
	) {
	continue;
	}
	if ( ! $wp_scripts->query( $handle, 'enqueued' ) ) {
	continue;
	}

[github-actions]

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[sirreal]

@luisherranz @youknowriad @swissspidy @gziolo I'd love to have your review on this approach to allowing classic scripts to depend on script modules.

[sirreal]

This is similar to what wp_dependencies_unique_hosts does:

wordpress-develop/src/wp-includes/general-template.php

Lines 3724 to 3726 in ef76060

	foreach ( array( $wp_scripts, $wp_styles ) as $dependencies ) {
	if ( $dependencies instanceof WP_Dependencies && ! empty( $dependencies->queue ) ) {
	foreach ( $dependencies->queue as $handle ) {

I'm not confident this is the most optimal way to get all classic scripts in the enqueued dependency graph so would appreciate scrutiny or domain knowledge on that.