AudioStreamPlayer not paused on pause mode change

[KoBeWi]

Godot version

3.x 0959ff2

System information

W10

Issue description

When you have AudioStreamPlayer and change its pause_mode, it will not get paused when it should.

Example code:
($AudioStreamPlayer has PAUSE_MODE_PROCESS)

func _ready() -> void:
	get_tree().paused = true
	$AudioStreamPlayer.play()
	yield(get_tree().create_timer(0.5), "timeout")
	$AudioStreamPlayer.pause_mode = Node.PAUSE_MODE_STOP # <- should stop playing here

Does not happen on master.

Steps to reproduce

1. Add AudioStreamPlayer
2. Add any long enough sound
3. Set pause_mode to Process
4. Add a script with the above code
5. Run and observe the player not pausing

Minimal reproduction project

No response

[pfertyk]

I'd like to submit a solution. It seems that, even though we save the new pause_mode, we don't send any notifications about it. I also added a check for can_process when unpausing AudioStreamPlayer (similar as pausing).

I tried to keep the code changes to minimum. This solution works for both cases (process => stop and stop => process), but I haven't check all combinations :) It's possible that we could use a new method here, like propagate_pause_mode. If so, let me know :)

[Reapetitive]

What is even worse, the sounds sometimes do not unpause! The stream_paused stays true, after unpausing.

[lawnjelly]

Fixed by #58577.