* brew completion in ZSH currently doesn't complete local formula files for most commands.
* Updating the completion script to complete formula files as well as known formulas in places that it would makes sense to do so.
* This includesFixes to __brew_formula_or_ruby_files
  * Remove redundant call to uncached brew search
  * Add missing ""

The brew file contains an incorrect completion for brew cask cleanup, which will yield an error as cleanup is deprecated from brew cask.

Aliases like instal and uninstal are unhelpful and noisy; don't offer them

See also PR #3052

Fixes #5839

- Eliminate reliance on external utility calls for cache invalidation
- Update cache policy to also invalidate if cache file is >=2 weeks old or if
  tap indexes are non-existent
- Do not override any cache policy the user might already have set
- Handle default cache policy determination as early as possible to ensure that
  a default is set appropriately for all helpers (this will mostly be useful if
  other helpers need caching in the future)

This reverts commit 4475651b.

These were deleted in cffa5a98.