Add adafruit matrix portal m4

[salsasteve]

Summary

Created pin mapping for adafruit matrix portal m4 board. Created a blinky basic example.

Checklist

• CHANGELOG.md for the BSP or HAL updated
• All new or modified code is well documented, especially public items
• No new warnings or clippy suggestions have been introduced (see CI or check locally)

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

[jbeaurivage]

Thank you for this. I added a few comments that need to be addressed, but good work in general. Specifically, this board will be a Tier 2, so its dependency on atsamd-hal should not be a path dependency but rather use the crates.io version.

[salsasteve]

Thank you for the review. I have fixed the issues above and retested the board again

[jbeaurivage]

@salsasteve, I'm sorry, seems like I was mistaken regarding the critical-section-single-core feature. Looks like all other BSPs enable it. Can you please reenable it? Everything else looks good, so I will merge as soon as it's done.