fibocom: Initial EPS bearer support

As discussed in this thread: https://lists.freedesktop.org/archives/modemmanager-devel/2022-August/009373.html

This almost works, however, I run into the following problem:

1. The profile manager detects that profile 1 can be re-used (log line 1026)
2. The profile is detected to be active (log line 1033)
3. Tearing down the initial EPS bearer makes the modem detach and the subsequent +GTRNDIS=1,1 failes (log line 1047)

@aleksm how do you suggest to handle this?

mm.log