Unpack the mms and save attachments

This also adds initial display support via uri link and deletes the
MMSD message.

Signed-off-by: Kyle Evans <kvans32@gmail.com>
3 jobs for mmsd in 4 minutes and 16 seconds (queued for 1 second)
Status Name Job ID Coverage
  Build
passed build-debian-gcc-buster #312773
librem5

00:00:49

 
  Package
passed package:deb-debian-buster #312774
librem5

00:00:57

passed package:deb-debian-buster:arm64 #312775
librem5:arm64

00:03:25