Format with air

[hfrick]

closes #168

This does a few things:

• set up the standard configuration of air: this basically turns on air when working in Positron/VSCode
• add 2 GHA: one checks that the code is formatted according to air's rules, the other one opens code suggestions on a PR to align the formatting (if necessary). The second one allows contributors to use air formatting, even when they don't have air installed/set up.
• tweaks air's config for spatialsample: the template for vcts is currently exempt
• finally: run air over the whole thing

Does that work for you? What's your IDE these days?

[hfrick]

Haha, failing the air action in the "let's use air" PR 😂 My air version locally is behind the GHA one! Lemme fix that

[hfrick]

The failing test-coverage action is fixed in #173.

[hfrick]

@mikemahoney218 This PR makes it a lot easier for us to drop by and and do little maintenance things because we'd not also get hit by the formatting changes. I'll leave it open for another week or so for you to shout if this messes badly with your workflow, but otherwise I'll take the liberty to merge. (If you don't use air, this PR includes a GHA workflow that will do the formatting for you as suggestions that you can batch accept.)