* Ability to use trailer with server injected frames
A 32-byte trailer generated per room.
Trailer appended when track encryption is enabled.
* E2EE trailer for server injected packets.
- Generate a 32-byte per room trailer. Too reasons for longer length
o Laziness: utils generates a 32 byte string.
o Longer length random string reduces chances of colliding with real data.
- Trailer sent in JoinResponse
- Trailer added to server injected frames (not to padding only packets)
* generate
* add a length check
* pass trailer in as an argument