Setup arm64 linux/windows runners for AOT releases

[ntkme]

https://github.blog/2024-06-03-arm64-on-github-actions-powering-faster-more-efficient-build-systems/

Specifically this can address the following:

dart-sass/.github/workflows/build-linux-musl.yml

Lines 23 to 28 in 5ddd7fc

	# There is a bug in qemu's mremap causing pthread_getattr_np in musl to stuck in a loop on arm.
	# Unless qemu fixes the bug or we get a real linux-arm runner, we cannot build aot-snapshot
	# for arm on CI. So, we create a kernel snapshot for arm build in amd64 container instead.
	# https://gitlab.com/qemu-project/qemu/-/issues/1729
	- arch: arm
	platform: linux/amd64 # linux/arm/v7

It allows us to build AOT for linux-arm-musl directly, as QEMU wasn't working. The Ampere CPU used by GitHub hosted runners is compatible with 32-bit arm. We can also build arm64 on arm64 runners instead of QEMU, which can speed up the build.

dart-sass/.github/workflows/build-windows.yml

Lines 21 to 22 in 5ddd7fc

	- arch: arm64
	runner: windows-latest

It allows us to build aot for windows-arm64.

@nex3 These would require setting up two paid runners, one for linux and one for windows. As we did setup a paid macos runner in the past, is this something you can help look into?

[nex3]

For windows, don't we have to build a script snapshot anyway to avoid code signing issues?

[ntkme]

For windows, don't we have to build a script snapshot anyway to avoid code signing issues?

As long as we're not building self-contained exe, there is no code sign issue. The production release of dart runtime and dartaotruntime should be both be pre-signed. The code sign issue comes from appending snapshot to any kind of runtime exe to create a self-contained file, which invalidates the signature.

Our windows x64 release is currently AOT.

[nex3]

I believe all you'd need to do to get these runners going is declare them in the actions file—they should pull from the same spending pool as the existing paid runners.

[ntkme]

These arm runners are not public free tier, which need to be created first via https://github.com/organizations/sass/settings/actions/runners, and then it can be specified with the name define during creation.

[nex3]

All right, I've created runners named linux-arm64 and windows-arm64.