Expose AudioServer::free(RID rid) as AudioServer.free_rid(RID rid)
Created by: Faless
To avoid script error due to collision with Object method free.
Calling AudioServer.free(rid) (eg. to delete a sample) currently cause the following error: "Invalid call to function 'free' in base 'AudioServerSW'. Expected 0 arguments".
This patch creates expose the method to free a specific resource as AudioServer.free_rid(rid) as done for example in Physics2DServer and PhysicsServer