Refactor release builds, add aarch64-musl

[alexcrichton]

This commit refactors the way release builds are done in CI in terms of configuration and then additionally adds aarch64-musl release artifacts as requested in #9875. The refactoring here is done to reduce the number of locations to understand release builds. Notably the binary-compatible-builds action was removed in favor of direct environment configuration in conjunction with docker images used to build. The aarch64-musl build itself happens in a container provided by the cross project to ensure that the right toolchain is configured.

Closes #9875

[alexcrichton]

@whitequark from this CI page if you scroll to the bottom and find bins-aarch64-musl (here's a direct link, not sure if that'll work) can you test that out? Mostly just make sure ./wasmtime --help does something and maybe poke at the commands a bit. If that works I think this is probably good to go to eventually get integrated into wasmtime-py

[whitequark]

OK so here is what I get if I run wasmtime in alpine edge on aarch64:

[whitequark]

I think this might be Alpine-specific, for some reason libgcc isn't installed by default? Anyway, after I fixed that, it ran and executed a real Wasm application (nextpnr).

[alexcrichton]

Ok perfect, thanks! I still don't know how to best manage libgcc_s on musl but it's at least no worse-off than the x64 target which I believe has the same behavior.