fractal-gtk: Use clap to set verbosity for release builds

By default, a release build of Fractal will only log errors.
A debug build will use the max level for development
purposes.

Running `fractal -v` will get users the same verbosity as
the debug build. Subsequent `-v`s will use increased
verbosity that will include extra info from our dependencies.
4 jobs for <span class="ref-name">wip/christopherdavis/use-loggerv</span> in 19 minutes and 31 seconds (queued for 1 second)
Status Job ID Name Coverage
  Check
passed #238348
check

00:00:26

 
  Test
passed #238349
flatpak

00:17:35

 
  Review
passed #238350
review

00:01:07

failed #238351
allowed to fail manual
stop_review

00:00:22

 
Name Stage Failure
failed
stop_review Review
Using Docker executor with image fedora:29 ...
Pulling docker image fedora:29 ...
Using docker image sha256:d7372e6c93c6c7b925600981b655c94829515a37cf876ff9e6d0287ff2b739d9 for fedora:29 ...
Running on runner-d836cf30-project-164-concurrent-0 via gcc150.bak.milne.osuosl.org...
Cloning repository...
Cloning into '/builds/BrainBlasted/fractal'...
Checking out 8995697f as wip/christopherdavis/use-loggerv...
fatal: reference is not a tree: 8995697f54fd906498b6f759b31b7ef83f064a1c
ERROR: Job failed: exit code 1