pmbootstrap status: rework (MR 2294)

Reimplement "pmbootstrap status" to be just a simple and useful status
overview. The previous version ran a bunch of checks every time, and
would fail on these even if pmaports was used for normal development:
  * "non-official" branch checked out in pmaports
  * pmaports.git is not clean

The information about aports.git was also considered not so useful upon
revisiting this command, since it is only used for "pmbootstrap
aportgen". Most users don't need this, and if the user runs this
command, it will tell if aports.git is outdated.

All of the above made the previous version unpleasant to use and I
suspect most people stopped using the command after trying it out a few
times and seeing the irrelevant but loud NOK complaints.

New version:

  $ pmbootstrap status
  Channel: edge (pmaports: master_staging_systemd)
  Device:  qemu-amd64 (x86_64, kernel: virt)
  UI:      console
  systemd: no (default for selected UI)

Old version (without --details it only shows NOK checks):

  $ pmbootstrap status --details
  [00:55:20] *** CONFIG ***
  [00:55:20] Device: qemu-amd64 (x86_64, "QEMU amd64")
  [00:55:20] Kernel: virt
  [00:55:20] User Interface: console
  [00:55:20]
  [00:55:20] *** GIT REPOS ***
  [00:55:20] Path: /home/user/.local/var/pmbootstrap/cache_git
  [00:55:20] - aports_upstream (master)
  [00:55:20] - pmaports (master)
  [00:55:20]
  [00:55:20] *** CHECKS ***
  [00:55:20] [OK ] Chroots zapped recently (or non-existing)
  [00:55:20] [OK ] aports_upstream: on official channel branch
  [00:55:20] [OK ] aports_upstream: workdir is clean
  [00:55:20] [OK ] aports_upstream: tracking proper remote branch 'origin/master'
  [00:55:20] [OK ] aports_upstream: up to date with remote branch
  [00:55:20] [OK ] aports_upstream: remote information updated recently (via git fetch/pull)
  [00:55:20] [OK ] pmaports: on official channel branch
  [00:55:20] [OK ] pmaports: workdir is clean
  [00:55:20] [OK ] pmaports: tracking proper remote branch 'origin/master'
  [00:55:20] [OK ] pmaports: up to date with remote branch
  [00:55:20] [OK ] pmaports: remote information updated recently (via git fetch/pull)
  [00:55:20]
  [00:55:20] NOTE: chroot is still active (use 'pmbootstrap shutdown' as necessary)
  [00:55:20] DONE!

pmb/parse/arguments.py

@@ -551,9 +551,7 @@ def arguments_lint(subparser):
 
 def arguments_status(subparser):
     ret = subparser.add_parser("status",
-                               help="quick health check for the work dir")
-    ret.add_argument("--details", action="store_true",
-                     help="list passing checks in detail, not as summary")
+                               help="show a config and pmaports overview")
     return ret