ci: use setup-cross-toolchain-action instead of cross

[taiki-e]

We are currently using cross, which does not work with the tokio test suite.

setup-cross-toolchain-action is a GitHub Action to set up CI environment for cross-testing, including doctest, without dockers.

This allows our CI to run tests for various architectures.

This patch includes:

• Run test and doctest for aarch64, arm, i686, powerpc64le, mipsel, mips64el, riscv64gc, s390x linux. (Previously, it was build only.)

  • Tested targets are based on architectures officially supported by debian,ubuntu,fedora

    debian: https://wiki.debian.org/SupportedArchitectures (the following list doesn't include unofficially supported arch)

    • x86
    • x86_64
    • arm (v5t, v7hf)
    • aarch64
    • mips64el
    • mips (deprecated in debian 10)
    • mipsel
    • powerpc64le
    • s390x

    ubuntu: https://help.ubuntu.com/community/SupportedArchitectures

    • x86
    • x86_64
    • arm (v7hf)
    • aarch64
    • powerpc64le
    • s390x

    fedora: https://fedoraproject.org/wiki/Architectures

    • x86_64 (Primary Architecture)
    • arm (v7hf, Primary Architecture)
    • aarch64 (Primary Architecture)
    • mips64el
    • mipsel
    • powerpc64le
    • riscv64gc
    • s390x

• Build for android and aarch64 windows. (setup-cross-toolchain-action doesn't support testing of them)

Closes #3424
Closes #2985 (aarch64 windows)
Closes #4454 (mipsel linux meets this)

[Darksonn]

What's the status on this?

[carllerche]

I think we can close this. It looks like cross test works now.

[carllerche]

(If I am wrong, we probably should resume work in a new PR at this point).