Enable TLS in the internal network for RabbitMQ

Enable TLS in the internal network for RabbitMQ

This optionally enables TLS for RabbitMQ  in the internal network. Note
that this leaves enable_internal_tls as undef instead of using the
regular default. This is because we don't want to enable this just now,
since we first want to pass the necessary hieradata via t-h-t. This will
be cleaned in further commits.

bp tls-via-certmonger
Depends-On: I4f37e77ae12e9582fab7d326ebd4c70127c5445f
Depends-On: Ic32b2cb253fa0dc43aad7226b24919b7e588faa9
Change-Id: Ic2a7f877745a0a490ddc9315123bd1180b03c514