[5.0][RFC][Events] Make Editor and Buttons plugins to use plugin events

[Fedik]

Summary of Changes

The patch improve Editor and Buttons plugins.
Now they can use a real events.
It similar to #39657 but for Editors and Buttons.

This is fully backward compatible.

How this work.
Here I added a new event onEditorSetup and an Interface for EditorProviderInterface class.
And similar for buttons onEditorButtonsSetup and a Button class with Interface ButtonInterface.

On onEditorSetup an editor plugin should register own EditorProvider in EditorsRegistry.
On onEditorButtonsSetup a button plugin should register own Button(s) in ButtonsRegistry.

The system will retrieve a requested Editor from that registry and call required methods, that defined by EditorProviderInterface.

Example registering an Editor:

joomla-cms/plugins/editors/codemirror/src/Extension/Codemirror.php

Lines 50 to 55 in 059d2b4

	public function onEditorSetup(EditorSetupEvent $event)
	{
	$this->loadLanguage();
	$event->getSubject()->add(new CodeMirrorProvider($this->params, $this->getApplication(), $this->getDispatcher()));
	}

Example registering an editor Button:

joomla-cms/plugins/editors-xtd/article/src/Extension/Article.php

Lines 58 to 73 in 059d2b4

	public function onEditorButtonsSetup(EditorButtonsSetupEvent $event)
	{
	/** @var ButtonsRegistry $subject */
	$subject = $event->getSubject();
	$disabled = $event->getDisabledButtons();
	if (\in_array($this->_name, $disabled)) {
	return;
	}
	$button = $this->onDisplay($event->getEditorId());
	if ($button) {
	$subject->add($button);
	}
	}

Testing Instructions

Apply patch.
Set default editor to Codemirror and make sure it works.

Testing B/C:
Enable TinyMCE editor and make sure it works.

Actual result BEFORE applying this Pull Request

Works

Expected result AFTER applying this Pull Request

Works

Link to documentations

Please select:

• Documentation link for docs.joomla.org: https://docs.joomla.org/Plugin/Events
• Pull Request link for manual.joomla.org: Editor and Editor buttons (XTD) plugins Manual#97

[HLeithner]

Can you please create a manual entry for migration, not only that it changes, also what needs to be done to convert a button to use event triggers please.

I'm merging this for now to have more test coverage in alpha.

[Fedik]

Do not forget the same for Cpatcha:

• [5.0][RFC][Events] Make captcha plugins use plugin events #39657

Also would be good to have a decision about following, client side api:

• [5.0][RFC] Joomla.Editor and Joomla.EditorButton client side API #40202

Which depend from Dialog PR #40150