[Bug]: tab completion issues

[gregmagolan]

A few issues to note here reported by users:

1. brew installation of aspect CLI doesn't properly install /opt/homebrew/share/zsh/site-functions/_bazel (or _aspect) which breaks zsh completions.
2. I can aspect completion zsh > /opt/homebrew/share/zsh/site-functions/_aspect to get completions but since some users are expecting to use bazel as the CLI name, it doesn't get picked up. And writing it to _bazel doesn't seem to work
3. performance of flag completion observed to be a little sluggish. aspect test --test<TAB> takes around 1s and I can see in the terminal bar that a few processes are launched, can this be streamlined?
4. completion of targets is too slow to be usable, aspect test //services:partially_migrated_dev<TAB> takes 4s to complete

Interestingly I've observed that performance in bash is much better than zsh.