Rotation APIs: Better exposure for degrees methods

Made public the various set/getters for rotations in degrees.
For consistency, renamed the exposed method names to remove the leading
underscore, and kept the old names with a deprecation warning.

Fixes #4511.

misc/tween/main.gd

@@ -108,7 +108,7 @@ func reset_tween():
 		sprite.set_scale(Vector2(1,1))
 	
 	if get_node("modes/rotate").is_pressed():
-		tween.interpolate_method(sprite, "_set_rotd", 0, 360, 2, state.trans, state.eases)
+		tween.interpolate_method(sprite, "set_rotd", 0, 360, 2, state.trans, state.eases)
 		tween.interpolate_property(sprite, "transform/rot", 360, 0, 2, state.trans, state.eases, 2)
 	
 	if get_node("modes/callback").is_pressed():