[pp-2] Move hook_implementations_map generation to late in service container compilation to make altering hooks classes more DX friendly

Problem/Motivation

The way hook_implementations_map is created alongside adding kernel.event_listener tags makes it difficult for other compiler passes to conditionally undefine hook classes with their own criteria. If you want to undefine the hooks class, you must also update the hook_implementations_map parameter at the same time. And doing so requires either either: hardcoding the unsets for each method, use reflection to find the hooks to undefine, or loop through all implementations which is very non-performant.

See also thread at https://git.drupalcode.org/project/drupal/-/merge_requests/12156#note_51... . A code comment has been added to that MR, referencing this issue.

Proposed resolution

Generating hook_implementations_map should be deferred to very late in the container building process since it is just a memoization of what was discovered, at least with a very late weight/priority in the current compiler pass order. Or perhaps use a different compiler pass later than the existing existing\Symfony\Component\DependencyInjection\Compiler\PassConfig::TYPE_BEFORE_OPTIMIZATION. See \Symfony\Component\DependencyInjection\ContainerBuilder::addCompilerPass. This call currently happens in \Drupal\Core\CoreServiceProvider::register.

If a parameter is still used, it should be renamed and prefixed with a `dot`, to signify it's internal. Combined with a [class] constant of some kind to keep things referential. From Symfony docs:

By convention, parameters whose names start with a dot . (for example, .mailer.transport), are available only during the container compilation. They are useful when working with Compiler Passes to declare some temporary parameters that won't be available later in the application.

I Imagine this kind of internal parameter doesn't have BC, so existing can be reworked.

Better yet, undefine the parameter after using it. Or, not use a parameter

My suggestion is:

• Remove map in \Drupal\Core\Hook\HookCollectorPass::writeImplementationsToContainer
• Remove parameter
• Tag the service with the origin $module. The other metadata, $priority & $method, is already in kernel.event_listener. $class is the service itself.
• Late in service compilation, create a map from service tags and set the parameter value in \Drupal\Core\Extension\ModuleHandler::$hookImplementationsMap directly, instead of via a service container parameter.

Remaining tasks

Implement suggested.

User interface changes

None.

Introduced terminology

None.

API changes

Removed parameter.

Data model changes

None.

Release notes snippet

None.