Set if the current user's destination and session is joinable while keeping the other group presence parameters the same. If the destination or session ids of the user is not set, they cannot be set to joinable.A message with type
ovrMessage_GroupPresence_SetIsJoinable will be generated in response.First call
ovr_Message_IsError() to check if an error occurred.This response has no payload. If no error occurred, the request was successful. Yay!