feat(integrity): Allow to run check for all apps

[SystemKeeper]

Summary

Example:

✗ occ integrity:check-app --all
encryption: 1 errors found:
  - EXCEPTION:
    - class: OC\IntegrityCheck\Exceptions\InvalidSignatureException
    - message: Signature data not found.
settings: 1 errors found:
  - EXCEPTION:
    - class: OC\IntegrityCheck\Exceptions\InvalidSignatureException
    - message: Signature data not found.
comments: 1 errors found:
  - EXCEPTION:
    - class: OC\IntegrityCheck\Exceptions\InvalidSignatureException
    - message: Signature data not found.
activity_back: App signature not found, skipping app integrity check
...

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)