Fix tinymce on-demand loading

[cconard96]

Checklist before requesting a review

• I have read the CONTRIBUTING document.
• I have performed a self-review of my code.

Description

TinyMCE is currently loaded in two ways:

• Sector-based inclusion
• On-demand just before initializing the editor on a textarea

Neither of these cases are very good.

The first case technically works, but there can be some cases where the library is loaded for no reason. For example, it was included for the central page but its only ever actually used if you click on an event in the planning widget which loads the Reminder/Event form in a modal. If you don't actually initialize an editor, you have a 680kb script (non-minified size) being loaded for nothing.

The second case makes more sense, except that it doesn't actually load the library if initialized any time after includeHeader is called because initEditorSystem calls requireJs. Instead, it adds the library to the session property and would have it automatically load the next time includeHeader is called (page refresh). This is how you end up with bugs like #3663. The solution for the referenced issue was to just load the library for the entire central sector which is more of a workaround than addressing the actual issue.

You could directly import the required scripts by adding script tags with the src attribute set inside initEditorSystem, but that would load them multiple times if there are multiple editors.

The solution here is to move the initialization into its own script which imports the extra JS files and then use dynamic imports to ensure the module is only loaded once but still allows initializing multiple editors.

[trasher]

See @AdrienClairembault comment

[AdrienClairembault]

Placeholder styles seems to not be fully loaded.

On main:

With your changes:

There are a lot of extra padding and the text color isn't right.

edit: the cursor seems also wrong, it not longer have the text appearance.

[AdrienClairembault]

It seems to now work for some placeholders but not all:

In this example the second one doesn't have the correct color.

Padding issues seems to be mostly resolved, there is still some additional left padding that seems to be applied when compared to main but I can live with it.

Nevertheless, maybe it mean the styles are not fully charged so it might be worth investigating because there might be other issues that we may miss here.

[cconard96]

I've reverted back to the oxide skin to unblock this PR. I'll work on fixing it in a different PR.

[cedric-anne]

Tests are still failing.