Add an xtask package to simplify our CI workflow

[jessebraham]

This turned out to be a bit bigger of a project than anticipated, but this PR should close 4 issues so that's a win at least 😁

• Added an --output-path option so that we can generate the projects in arbitrary directories
  • This is so that the xtask can generate projects in temporary directories, to avoid polluting the workspace when run locally
• Removed the stack-protector options (closes Remove stack-protection #16)
• Created the xtask package to simplify our CI workflow (closes Add support for xtask to simplify checks #11)
• Updated the CI workflow to use xtask package and run unit tests (closes CI: Run unit tests #13)
• Removed the extraneous HAL initialization call from async_main.rs (should close Generated code leads to runtime panic #21)

The output of the checks are a bit noisy, maybe we want to avoid displaying stdout and stderr to make the logs a bit more readable?

I've also just copied the combinations of features from the existing workflow, perhaps we want to check more?

Happy to make any changes, lemme know what you guys think.

[SergioGasquez]

LGTM! Thanks for fixing/improving so many things!

Current CI takes about 14 mins, we may want to check all the combinations for every chip, but that will increase the CI time. Maybe run it daily instead of running it per commit? This would catch issue like #19 #20

[MabezDev]

Current CI takes about 14 mins

Unlike esp-hal, I see this repo getting less and less activity as it stabilizes. Imo CI time is less of a concern here, but I'll leave it with you guys for the final call.

[bjoernQ]

Current CI takes about 14 mins

Unlike esp-hal, I see this repo getting less and less activity as it stabilizes. Imo CI time is less of a concern here, but I'll leave it with you guys for the final call.

Wanted to write the same comment - if this assumption turns out to be wrong,, we can reconsider it

[bjoernQ]

Thanks!