Move pseudolocalization into TranslationDomain

[timothyqiu]

Follow-up to #95787
Partially supersedes #96105

This PR:

• Moves pseudolocalization related functions into TranslationDomain. So they can be changed per translation domain.
• Adds --editor-pseudolocalization command-line option to turn on pseudolocalization for the editor and project manager at startup.

How plugins toggle their pseudolocalization

# On the plugin's root UI node
var domain := TranslationServer.get_or_add_domain(get_translation_domain())
domain.pseudolocalization_enabled = enable
# put other pseudolocalization related configurations here
propagate_notification(NOTIFICATION_TRANSLATION_CHANGED)

Demo project: test-4.zip

How to toggle editor pseudolocalization

The pseudolocalization of the project manager and editor can be enabled by using the command line parameter --editor-pseudolocalization.

To toggle pseudolocalization of the editor at runtime, run this editor script:

@tool
extends EditorScript

func _run():
    var domain := TranslationServer.get_or_add_domain("godot.editor")
    domain.pseudolocalization_enabled = not domain.pseudolocalization_enabled
    EditorInterface.get_base_control().propagate_notification(MainLoop.NOTIFICATION_TRANSLATION_CHANGED)

Note that this script is meant for editor developers. The domain name godot.editor is an implementation detail. It might change without considering (i.e., breaking) existing editor scripts.

Why you need to propagate TRANSLATION_CHANGED yourself

Regular users toggle pseudolocalization for their projects via TranslationServer.pseudolocalization_enabled = enabled. This will automatically emit NOTIFICATION_TRANSLATION_CHANGED. So does the previous workflow of modifying Project Settings and calling TranslationServer.reload_pseudolocalization().

Dealing with translation domains is advanced usage:

• It's better to emit the notification after batch modifying pseudolocalization related properties.
• It's not clear which subtrees are using a specific translation domain. Therefore, it's more efficient to let the caller decide the scope of the propagation.

[KoBeWi]

Is editor pseudo-localization supposed to add text to otherwise textless buttons?

(though I guess it's unrelated to this PR)

EDIT:
Inspector is not pseudo-localized

but it spits error when you hover property

EDIT2:
Pseudo-localized placeholder

[KoBeWi]

Aside from the issues mentioned above, it works correctly.

[timothyqiu]

Is editor pseudo-localization supposed to add text to otherwise textless buttons?

Yes. This is the same behavior when pseudo-localization is enabled in game projects. Maybe pseudo-localization can skip empty strings. We can tweak this behavior in a later PR.

Inspector is not pseudo-localized

Labels in inspectors are not subject to auto translation.

but it spits error when you hover property

It seems that tooltip texts always go through atr() currently. I'll see what can we do about it. Fixed by #97406.

[akien-mga]

@bruvzg Does this approach look good to you? You have a conflicting PR #96105 so I'd like to make sure we have the best of both worlds here.

[bruvzg]

Does this approach look good to you?

Yes, this is a better way to handle it. I'll update the remaining part of #96105 (number formatting) after this one is merged.

[akien-mga]

Thanks!