Admin Toolbar Tools: Remove dependency on Admin Toolbar

This is a follow-up to: #3554658: Admin Toolbar Search: Remove dependency on Admin Toolbar

Problem/Motivation

After removing the dependency on Admin Toolbar in submodule Admin Toolbar Search and the recent work carried on refactoring the Admin Toolbar Tools module tests, it appeared the module still has a dependency on Admin Toolbar.

Theoretically, there is no reason the Admin Toolbar Tools module could not work properly without the Admin Toolbar module and in fact.... without any dependency.
See dependency in the code:
https://git.drupalcode.org/project/admin_toolbar/-/blob/3.6.2/admin_tool...

Additionally, it could really help further clarifying the role of each module:

• Admin Toolbar: Provides the JS dropdown menu features (Mostly front-end logic adding JS libraries).
• Admin Toolbar Tools: Provides extra links for Tools (such as flush cache, etc...) or for configuration pages under: "Content", "Structure", "Configuration", "People", etc... Along with useful links integrated with other contrib modules, such as devel, project_browser, etc... (Mostly back-end logic adding links).

 
Looking at the code, there doesn't seem to be any reason this dependency would be necessary, in the sense, the module does not seem to use any feature from the admin_toolbar module, whether, JS, CSS, images, etc...

In other words, the impacts and changes that could be required would be very limited, while still allowing to decouple entirely the modules to provide more flexibility.
The idea behind that is to try to make the code packages as granular as possible, with only the dependencies that are really required in code.

An immediate application of this change would be the ability to enable admin_toolbar_tools along with the Drupal core Navigation module to add extra links, for example, under "Structure", such as "Content types", etc...

Steps to reproduce

Enable the admin_toolbar_tools module ==> Requires admin_toolbar to be enabled.

To uninstall the admin_toolbar module, the admin_toolbar_tools module needs to be uninstalled first.

Proposed resolution

Remove any dependency:
admin_toolbar_tools.css: The styles of the module should work fine with the Toolbar module enabled and they should not be loaded otherwise.

ToolbarController: All the services injected in the create method are from core.services.yml, so no extra dependency should be required as long as Drupal core is loaded.
Note that function views_invalidate_cache (requiring Views) used by the "Flush views cache" menu link is not directly linked in the links.menu.yml of the module, but is conditionally added as a link in the 'Extralinks' class if the Views module is enabled.
In other words, there should not be any required dependency.

ExtraLinks: It is a plugin derivative class which is triggered by MenuLinkManager which is also part of Drupal core services. All the code of the method getDerivativeDefinitions should be able to run properly with any dependency being checked.

AdminToolbarToolsHelper and admin_toolbar_tools.services.yml: All the services dependencies are on Drupal core services ==> No extra dependency needed.

admin_toolbar_tools.module: It should be fine to keep all the hooks as they currently are.
They just would not be triggered if the corresponding module is not enabled, for example: Toolbar, etc...
But it should not prevent the use of the rest of the module, for example ExtraLinks.

Impacted files:
admin_toolbar_tools.info.yml: Remove dependency constraint.
https://git.drupalcode.org/project/admin_toolbar/-/blob/3.6.2/admin_tool...

AdminToolbarToolsSettingsFormTest
https://git.drupalcode.org/project/admin_toolbar/-/blob/3.6.2/admin_tool...
Enable the 'admin_toolbar' module for the tests.

AdminToolbarToolsToolbarControllerTest
https://git.drupalcode.org/project/admin_toolbar/-/blob/3.6.2/admin_tool...
Enable the 'admin_toolbar' module for the tests.

AdminToolbarToolsSortTest
https://git.drupalcode.org/project/admin_toolbar/-/blob/3.x/tests/src/Fu...
Enable the 'admin_toolbar' module for the tests.

Add a simple Functional test class to test the module without admin_toolbar:
AdminToolbarToolsTest.php
or adapt new ones refactored in other issue/ticket.
Enable admin_toolbar_tools and check specific menu links added by the module.
 

The rest of the code should stay unchanged, in particular all the Automated tests and the module should work very well with the current dependencies.

Remaining tasks

User interface changes

When enabling the admin_toolbar_tools module, the admin_toolbar module will no longer be enabled at the same time, but users will have to enable/select it manually as well.

Before:
Select admin_toolbar_tools to be enabled ==> Enabled admin_toolbar_tools and admin_toolbar.

After:
Select admin_toobar_tools to be enabled ==> Enabled admin_toolbar_tools.

Select admin_toobar_tools and admin_toolbar ==> Enabled admin_toolbar_tools and admin_toolbar.

Select admin_toolbar_tools and admin_toolbar_search ==> Enabled admin_toolbar_tools and admin_toolbar_search.

API changes

Data model changes