feat: new brew-updates plugin which also replaces homebrewcask plugin

[jimeh]

New brew-updates plugin which supports:

• Showing outdated formulas, casks, and pinned formulas, with details about exact version numbers.
• Upgrading:
  • Individual formulas and casks.
  • All formulas.
  • All casks.
  • All formulas and casks.
• Pinning and unpinning formulas.
• Uninstalling formulas, casks, and pinned formulas.

This can safely replace the existing homebrewcask plugin, especially as it seems to have been broken ever since Homebrew removed the "cask" sub-command.

It can also replace the existing brew-updates plugin, which is very basic in that it simply lists all outdated formulas and casks, with the only action available being to upgrade, without showing details about current/latest versions.

---

I'm not sure what the policy is on removing existing plugins, so apologies if simply removing them in a PR like this is not the right way to go about it. I'm happy to change anything as needed :)

Screenshots

New brew-updates:

Old brew-updates (removed):

homebrewcask (removed):

[jimeh]

Apologies for the force pushes. I've simply been updating my PR's here to include updates/fixes I've been making in my dotfiles.

That said, I do not expect to make any further changes for some time, as I've now resolved all annoyances I've had with this script.

[sprak3000]

@jimeh

Looks like the branch has a conflict. Could you clear that up?

[jimeh]

@sprak3000 all done, rebased on top of the lastest state in main, and also updated the script with a minor update from my dotfiles.