Add cross-compilation builds

[pavelzw]

• Adds cross-compilation builds for linux-aarch64, linux-ppc64le and osx-arm64
• Switches from custom compilation steps to conda-forge feedstock compilation steps
• Remove Don't run this job branches because it is very slow in the Windows static build since the Windows static build takes about 30min (~22 with caching) which is still faster than the regular CI

I didn't manage to get the conda-build pipeline working for Windows in reasonable time and since we already have build instructions for Windows, I guess that's okay.

One issue we have is that the Linux and macOS builds don't use caching any more... But since they take less time than the regular CI pipeline even without caching, it should be okay...

Closes #1887

[jonashaag]

This looks really nice now. Thanks a bunch! Do you consider this ready to merge?

[pavelzw]

Do you consider this ready to merge?

If you don't have anything more to add and the CI passes, you can merge it 👍🏻

[jonashaag]

sed -z is a nice hack to do multiline replacements with sed :)

[pavelzw]

sed -z is a nice hack to do multiline replacements with sed :)

Unfortunately only works on GNU sed :(

[jonashaag]

It could be that we have gsed in the macOS runners. I think it's from the Homebrew coreutils package.

[pavelzw]

It could be that we have gsed in the macOS runners. I think it's from the Homebrew coreutils package.

Unfortunately not.