wireprotov2: change frame type and name for command response There was hole at frame type value 3. And the frame is better named as a command response. Differential Revision: https://phab.mercurial-scm.org/D3384

wireprotov2: change frame type value for command data When we dropped the dedicated command argument frame type, this left a hole in our frame type numbering. Let's start plugging that hole. The command data frame is now type value 2 instead of 3. There was limited test fallout because a) we do a good job of using the constants to refer to frame types b) not many tests are sending command data frames. Bumping the media type will be performed in a later commit, once all type value adjustment has been performed. Differential Revision: https://phab.mercurial-scm.org/D3383