feat(testing): test on more architectures

[lczyk]

we are testing only on arm64 and amd64, but chisel supports other archs too. we should run the tests on more architectures (like, for example, riscv64).

to do this we should formalize patterns like these:

• https://github.com/canonical/chisel-releases/blob/a649c296dd059fa250ec914e17a1decafffe03b8/tests/spread/integration/binutils-aarch64-linux-gnu/test_hello.sh#L4C1-L13C3
• https://github.com/canonical/chisel-releases/blob/a649c296dd059fa250ec914e17a1decafffe03b8/tests/spread/integration/binutils/test_help_and_version.sh#L3C1-L13C3

• chisel-releases/spread.yaml

  Line 87 in a649c29

  arch="$(dpkg --print-architecture | sed -e 's/armhf/arm/g' -e 's/ppc64el/ppc64le/g')"

[lczyk]

@lengau fyi :) feel free to add / drop thoughts etc. alas, this is likely not a priority for this cycle, but definitely something we should do in the future

[lengau]

s390x and ppc64el should be fairly straightforward with Canonical's self-hosted runners (caveat: the runners are still experimental and could be disabled). If we're okay using our self-hosted runners using the existing spread tests can be used using the strategy in #655. The primary thing we'll depend on for that is having self-hosted runners for all our architectures, which is a deprioritised but ongoing discussion (risc-v probably being the last one that'll get that).