Bug 1095006 — Touch the RoomToken when touching the participant.

https://bugzilla.mozilla.org/show_bug.cgi?id=1095006
While I understand we need to have two different keys for the roomparticipant hawk token and tokbox token, I think the naming of the key isn't clear here.

Rather than having `roomparticipant.{roomToken}.{hawkIdHmac}` and `roomparticipant_token.{roomToken}.{hawkIdHmac}`, we probably should be more consistant in our naming.

From reading the code, it's not clear which key is associated to which piece of information. If what I understand is correct (it may not), then we could rename the `roomparticipant_token.` prefix by `roomparticipant_tb_token` and rename the other one by `roomparticipant_hawk_token`.