Let languages init & finish run without locks held

[RandomShaper]

These changes are still not perfect against race conditions, but that was already the case before the recent batch of changes here.

• Fixes Godot v4.2.beta.mono editor freezes when quitting. #84728.
• Fixes GDExtension project doesn't open properly with linux-editor-mono artifact after language bookkeeping thread-safety PR #84735.

[akien-mga]

It should also fix #84728 (the problem is with the C# bindings btw, not GDExtension - but GDExtension script bindings may also be affected).

[akien-mga]

I tested this today, and confirm this fixes #84728.

Didn't spot any obvious regression on a couple GDScript and C#.
Didn't test any GDExtension ScriptLanguage.

I still get this one error when closing the .NET editor, but it's no longer blocking:

ERROR: Condition "!EditorSettings::get_singleton() || !EditorSettings::get_singleton()->has_setting(p_setting)" is true. Returning: Variant()
   at: _EDITOR_GET (./editor/editor_settings.cpp:1140)

The same error happens in 4.2-beta5 so it's not related to your original PR, and thus not needed to fix here.
Edit: This error even happens in 4.1-stable on my test project.

[YuriSizov]

The same error happens in 4.2-beta5 so it's not related to your original PR, and thus not needed to fix here.
Edit: This error even happens in 4.1-stable on my test project.

It is probably related to this report #84839.

[akien-mga]

Thanks!