feat(files): Add help to / update description of `files:cleanup`

[joshtrichards]

• Resolves: #

Summary

After:

Output of occ files:

[...]
Available commands for the "files" namespace:
  files:cleanup                    Clean up orphaned filecache and mount entries
  files:copy                       Copy a file or folder
  [...]

Output of files:cleanup --help:

Description:
  Clean up orphaned filecache and mount entries

Usage:
  files:cleanup [options]

Options:
      --skip-filecache-extended  don't remove orphaned entries from filecache_extended
  -h, --help                     Display help for the given command. When no command is given display help for the list command
  -q, --quiet                    Do not output any message
  -V, --version                  Display this application version
      --ansi|--no-ansi           Force (or disable --no-ansi) ANSI output
  -n, --no-interaction           Do not ask any interactive question
      --no-warnings              Skip global warnings, show command output only
  -v|vv|vvv, --verbose           Increase the verbosity of messages: 1 for normal output, 2 for more verbose output and 3 for debug

Help:
  Deletes orphaned filecache and mount entries (those without an existing storage).

Before:

Output of occ files:

[...]
Available commands for the "files" namespace:
  files:cleanup                    cleanup filecache
  files:copy                       Copy a file or folder
[...]

Output of files:cleanup --help:

Description:
  cleanup filecache

Usage:
  files:cleanup [options]

Options:
      --skip-filecache-extended  don't remove orphaned entries from filecache_extended
  -h, --help                     Display help for the given command. When no command is given display help for the list command
  -q, --quiet                    Do not output any message
  -V, --version                  Display this application version
      --ansi|--no-ansi           Force (or disable --no-ansi) ANSI output
  -n, --no-interaction           Do not ask any interactive question
      --no-warnings              Skip global warnings, show command output only
  -v|vv|vvv, --verbose           Increase the verbosity of messages: 1 for normal output, 2 for more verbose output and 3 for debug

Historical context:

• cefdcea02171672d6340d9db57a54ffac78c5ab8

• 38933

• 21729

TODO

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)