Implement method lookup for method tracks

[chocola-mint]

Closes godotengine/godot-proposals#12436

This PR allows users to lookup method definitions by holding down Ctrl (or Command) and clicking keys in method tracks.

• The cursor is changed into a pointing hand when Ctrl (or Command) is held and hovering over a method key.
• If the method is found on the track target's script, (or base scripts) the script editor is made to jump to where the method is defined.
• If the method is a native (C++) method, the built-in help page is shown instead.
• If the method is not found, (like the bad_method example below) an editor warning is shown.
• The "Go to Definition" menu item is also added when right-clicking a method key, so this feature can also be used without knowing the shortcut.

godot-animation-player-method-lookup.mp4

[TokageItLab]

I tested and it basically works. Somehow the selected line is off by one line after, so that should be fixed but you can send a follow up PR later.

[chocola-mint]

Somehow the selected line is off by one line after, so that should be fixed but you can send a follow up PR later.

This is a quirk with ScriptEditor::script_goto_method, also used by ConnectionsDialog here:

godot/editor/connections_dialog.cpp

Line 1209 in 45fc515

if (scr.is_valid() && ScriptEditor::get_singleton()->script_goto_method(scr, cd.method)) {

You can find the same behavior when using the Node dock to jump to methods connected to a signal. Making a separate issue about this is probably a good idea.

[Repiteo]

Thanks!