Add garuda-update

[jstelzer]

if garuda-update is in our path use that instead of directly calling pacman/paru/powerpill. There's more stuff the update script does that you're just asking for problems if you upgrade partially.

Standards checklist:

• The PR title is descriptive.
• The code compiles (cargo build)
• The code passes rustfmt (cargo fmt)
• The code passes clippy (cargo clippy)
• The code passes tests (cargo test)
• Optional: I have tested the code myself
  • I also tested that Topgrade skips the step where needed

I created a feature request here:
#226

[s34m]

Please format it first before this PR can be merged.

[jstelzer]

Sorry if it's dense, but what do you want WRT format? Just rustfmt? Other than that I merged in dev (i based the original patch off of master due to not knowing your workflow).

[jstelzer]

Sorry if it's dense, but what do you want WRT format? Just rustfmt? Other than that I merged in dev (i based the original patch off of master due to not knowing your workflow).

[s34m]

Jup, was just about rust Mt and clippy warnings

[jstelzer]

danke schoen