Rename AudioStreamPlayer to AudioPlayer

[madmiraal]

Also renames:

• AudioStreamPlayer2D to AudioPlayer2D
• AudioStreamPlayer3D to AudioPlayer3D

Originally suggested by @dalexeev in #16863 (comment)
Salvage of #46997 that was closed.

Closes godotengine/godot-proposals#3624

[reduz]

Discussed with audio contributors and see no reason to do this change. Godot uses AudioStream as audio source, hence the node is an AudioStreamPlayer. This has been better explained in godotengine/godot-proposals#3624.

[madmiraal]

I've replied in godotengine/godot-proposals#3624 (comment)

In response to your separate point here:

Godot uses AudioStream as audio source, hence the node is an AudioStreamPlayer.

This is an implementation detail, which may be confusing the issue. Audio files, which are not streams, are converted into an AudioStream, which are then played through the AudioStreamPlayer. This doesn't make the player an AudioStream only player.

[reduz]

I will give a bit more depth on why this is likely not going to happen. For 4.0, we went strongly towards the direction of making node names more explicit on their function. Examples of this are:

• All 3D nodes now end in 3D
• Physics nodes had renames like RigidDynamicBody, SoftDynamicBody, etc.
• Others have more explicit renames such as MeshInstance3D, VisibleOnScreenNotifier, etc.

This node plays an AudioStream, which can be either a file or something else (like user generated audio, microphone stream, etc). If confusion arises (which is unlikely given there is not any other node called even similarly), it's better in this case to improve the documentation of AudioStream to note that an AudioStream can be a file or another type of stream.

In any case, if you want to leave this PR open I am fine, but for the time being you don't have my consensus to go forward with it.