Add Target for aarch64-unknown-uefi

[HTGAzureX1212]

This Pull Request adds a new rustc target configuration called aarch64-unknown-uefi.

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @jackh726 (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

[petrochenkov]

Hi.
What is the relation of this PR with #85357?
They were submitted at the same time and contain some similar issues (#85357 (comment)).

[joshtriplett]

In addition to any other potential issues, this also needs to meet the target tier policy requirements for a new tier 3 target. You'll need to full-quote the tier 3 requirements from https://doc.rust-lang.org/nightly/rustc/target-tier-policy.html and explain how you meet each of them.

[HTGAzureX1212]

Good morning @petrochenkov and @joshtriplett; I will write up the reason why this aarch64-unknown-uefi target meets the requirements of a Tier-3 Target later today, thanks.

[petrochenkov]

To avoid doing the same work in two PRs I'm going to close this PR in favor of #85357 which was opened 2 minutes earlier.
@HTG-YT, feel free to collaborate with @Andy-Python-Programmer there.

[HTGAzureX1212]

👌