Frodo airplayconflicts

fixed the conflicts and merged:

Commit:b93a152 - [airplay] - handle empty session ids from itunes
Commit:7f0b5c6 - [airplay] - refactor the playstate announcement by using the IAnnouncer interface
- also adapt to some new findings on revers engineering itunes airplay traffic (add sessioncounter to reverse event and fix http request formatting), fixes #14191 - use the include and namespace from the commit - the breakage is because of cptspiffs "split off IPlayer callback to a separate file" commit which is not backported and added an include in that file