cask/installer.rb: stop including Staged module

[apainintheneck]

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The original pr #13516 was closed because of failing tests which were resolved in pr #13545.

The idea here is to tackle the todo on line 32 of cask/installer.rb related to the including of cask/staged. There are two methods found in cask/staged which are #set_permissions and #set_ownership. Neither of these methods are called throughout the entire brew codebase. These methods are made available through the preflight, postflight and uninstall_postflight cask stanzas where a quick search shows they do get used and staged is now required in each of those dsl files.

[BrewTestBot]

Review period will end on 2022-07-13 at 00:58:44 UTC.

[BrewTestBot]

Review period skipped due to critical label.

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

[MikeMcQuaid]

@apainintheneck good to merge when you are! if you don't have merge rights yet: remind me and I'll grant them

[apainintheneck]

@MikeMcQuaid Honestly I forgot about this PR. I'll merge it in.