VideoPlayer: Fix reloading translation remapped stream

[akien-mga]

• Fixes VideoPlayer: Remaps not supported #43917.
• Reverts Document the lack of localization remapping support in VideoPlayer (reverted) #43920.

MRP ported from Godot 3 (might need opening a couple of times, there's some weirdness with the font):
VideoRemaps.zip

Notes

• For some reason, .ogv extension doesn't show up in the list of resources that can be picked from translation remaps. So one needs to select "All Files" to select .ogv files.
• A good UX improvement would be to parse the end of the file to see if it's a locale name, and automatically pre-select the matching locale (and country if relevant), so video_de.ogv should automatically select "German", and video_de_AT should automatically select "German (Austria)".
• This changes means that if the VideoStream resource changes while it's being played, the playback will stop. It's still possible for users to handle automatically restarting the playback when that happens, with something like this (modified from MRP):

extends Control

var is_playing := false

func _ready() -> void:
	$Video.stream.changed.connect(_on_stream_changed, CONNECT_DEFERRED)
	_on_EN_pressed()

func _on_stream_changed() -> void:
	if is_playing:
		_on_Play_pressed()

func _on_video_finished():
	is_playing = false

func _on_EN_pressed() -> void:
	TranslationServer.set_locale("en")

func _on_DE_pressed() -> void:
	TranslationServer.set_locale("de")

func _on_RU_pressed() -> void:
	TranslationServer.set_locale("ru")

func _on_Play_pressed() -> void:
	print("pressed")
	$Video.stop()
	$Video.play()
	is_playing = true

But it may not be easy to seek to the previous position. To do so, we would need to only emit changed, but not handle in the VideoStreamPlayer, leaving it to the user to implement.

Alternatively the VideoStreamPlayer could have more signals like stream_changed that could include relevant information about the previous state (was playing, position, etc.). But the current player is fairly barebones and that's way outside the scope of this bugfix.

[KoBeWi]

For some reason, .ogv extension doesn't show up in the list of resources that can be picked from translation remaps. So one needs to select "All Files" to select .ogv files.

I investigated and it's caused by this:

godot/modules/theora/video_stream_theora.cpp

Lines 676 to 678 in d443f12

	bool ResourceFormatLoaderTheora::handles_type(const String &p_type) const {
	return ClassDB::is_parent_class(p_type, "VideoStream");
	}

The best part is that any resource with this method will not appear on the list. Consequently, any resource you can select does not implement handles_type(). I wonder what is this method for 🙃

[KoBeWi]

Shouldn't this comment be below, at connect()?

[akien-mga]

It was meant to cover both at once, but since they're split it's not very clear yeah.

[YuriSizov]

Cherry-picked for 4.2.1.

[YuriSizov]

Cherry-picked for 4.1.4. (Adjusted for the old API lacking connect_changed/disconnect_changed).