update to atsamd-hal-0.22 and other latest dependencies

[tboby]

Summary

This upgrades the Adafruit Neo Trinkey board to the latest hal version.

I mainly followed what other boards did while upgrading.

• An explicit dependency was added for cortex-m
• usb-device was upgraded to 0.3.1
• Examples were updated, and (most) clippy warnings resolved
• The usb_allocator doc string was corrected

Checklist

• All new or modified code is well documented, especially public items - No changes to API
• No new warnings or clippy suggestions have been introduced - CI will deny clippy warnings by default! You may #[allow] certain lints where reasonable, but ideally justify those with a short comment.

If Adding a new Board

• [ /] Board CI added to crates.json
• [ /] Board is properly following "Tier 2" conventions, unless otherwise decided to be "Tier 1"

If Adding a new cargo feature to the HAL

• [ /] Feature is added to the test matrix for applicable boards / PACs in crates.json

Note

The crate changelogs should no longer be manually updated! Changelogs are now automatically generated. Instead:

• If your PR is contained to a single crate, or a single feature:
  • Nothing else to do; your PR will likely be squashed down to a single commit.
  • Please consider using conventional commmit phrasing in the PR title.
• If your PR brings in large, sweeping changes across multiple crates:
  • Organize your commits such that each commit only touches a single crate, or a single feature across multiple crates. Please don't create commits that span multiple features over multiple crates.
  • Use conventional commmits for your commit messages.