Update protobuf definitions and Spotify versions

[drobotk]

Extracted from Spotify.dll version 1.2.96.518 using pbtk.

Worth noting:

• playlist4_external.proto is now playlist_api.proto
• playlist4_external::PlaylistModificationInfo message no longer exists. I copied it over into playlist_api.proto, but this needs investigating whether this message is still used
• social_connect_v2::Session.host_active_device_id field is no longer present in new definitions. I copied it back in because we use it, but this needs investigating whether this field is still used
• New AudioFile Format enum values:

PHONO_LOW = 54;
PHONO_HIGH = 55;
PHONO_CLEAR = 56;