Fix Cask::Cask.all bug

[apainintheneck]

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Fixes #16378

1. 5a674c2

Fix bug in Cask::Cask.all where we'd only read cask files and not attempt to load casks from the API JSON.

I ran a quick benchmark to make sure this isn't going to slow things down more than usual and it seems in the neighborhood so nothing to worry about from a performance perspective.

$ hyperfine \
  --parameter-list branch master,fix-cask-all \
  --warmup 2 \
  --setup 'git switch {branch}' \
  'HOMEBREW_EVAL_ALL=1 brew ruby -rformula -e \'Cask::Cask.all\''
Benchmark 1: HOMEBREW_EVAL_ALL=1 brew ruby -rformula -e 'Cask::Cask.all' (branch = master)
  Time (mean ± σ):     10.360 s ±  0.039 s    [User: 7.026 s, System: 2.639 s]
  Range (min … max):   10.291 s … 10.435 s    10 runs
 
Benchmark 2: HOMEBREW_EVAL_ALL=1 brew ruby -rformula -e 'Cask::Cask.all' (branch = fix-cask-all)
  Time (mean ± σ):      9.124 s ±  0.120 s    [User: 6.689 s, System: 2.043 s]
  Range (min … max):    9.015 s …  9.346 s    10 runs
 
Summary
  HOMEBREW_EVAL_ALL=1 brew ruby -rformula -e 'Cask::Cask.all' (branch = fix-cask-all) ran
    1.14 ± 0.02 times faster than HOMEBREW_EVAL_ALL=1 brew ruby -rformula -e 'Cask::Cask.all' (branch = master)

2. b797782

Resolve todo to remove ARGV references in Cask::Cask.all by adding the :eval_all parameter. I figured I'd just do this while I was in the area.

[apainintheneck]

@manuel-koch It would be great if you could test out the brew search command using this branch to double-check that this fix works for your use case.

[MikeMcQuaid]

Looks great, thanks again @apainintheneck!