fix: use record route header in bye

[AnshulMalik]

There are steps on how to form a request when record-route is present in the RFC: https://www.rfc-editor.org/rfc/rfc3261.html#section-12.2.1.1

If the route set is empty, the UAC MUST place the remote target URI
into the Request-URI. The UAC MUST NOT add a Route header field to
the request.

We are handling the above case well.

If the route set is not empty, and the first URI in the route set
contains the lr parameter (see Section 19.1.1), the UAC MUST place
the remote target URI into the Request-URI and MUST include a Route
header field containing the route set values in order, including all
parameters.

If the route set is not empty, and its first URI does not contain the
lr parameter, the UAC MUST place the first URI from the route set
into the Request-URI, stripping any parameters that are not allowed
in a Request-URI. The UAC MUST add a Route header field containing
the remainder of the route set values in order, including all
parameters. The UAC MUST then place the remote target URI into the
Route header field as the last value.

We also need to send ALL these values as Route header, not just one, not implemented in this PR.

[emiago]

seems good to me