pakfire: Refactor status seperating UI and logic

pakfire: Refactor status seperating UI and logic

- Removed UI code from status function now returning hash with status
  properties.
- Removed function coreupdate_available as it is now not used anymore
- Added UI code to pakfire status routine
- Added meaningfull exitcode to status:
  - 2: Core update available
  - 3: Pak update available
  - 4: Reboot required
  - Error codes can be added together: 2+3 = 5 means both core update
    and pak update is available

Signed-off-by: Robin Roevens <robin.roevens@disroot.org>