[tracking] Building on aarch64-unknown-none

[Matheus Xavier]

This issue is intended to track progress on allowing the kernel to build for aarch64-unknown-none.

Blockers:
TODO: list here the blockers.

[Ethan]

#75 is a start to this.

[Mohit D Patel]

This being shelved as we have agreed to develop exclusively for x64 until reaching a MVP or the community decides otherwise.