fix(cross): replace external apk-anywhere image with inlined Alpine apk in Dockerfile.musl

[saku3]

Description

Musl builds were failing because the following Docker repository is not available, so I fixed the build process.

https://hub.docker.com/u/jorgeprendes420

build error

Dockerfile.musl:4
--------------------
   2 |     FROM $CROSS_BASE_IMAGE
   3 |     
   4 | >>> COPY --from=jorgeprendes420/apk-anywhere / /
   5 |     ENV MARCH=${CROSS_CMAKE_SYSTEM_PROCESSOR}
   6 |     RUN apk-init ${MARCH} ${CROSS_SYSROOT}
--------------------
ERROR: failed to build: failed to solve: jorgeprendes420/apk-anywhere: failed to resolve source metadata for docker.io/jorgeprendes420/apk-anywhere:latest: pull access denied, repository does not exist or may require authorization: server message: insufficient_scope: authorization failed
Error: 
   0: could not run container
   1: when building custom image
   2: when building dockerfile
   3: `docker buildx build --progress auto --label 'org.cross-rs.for-cross-target=aarch64-unknown-linux-musl' --label 'org.cross-rs.runs-with=x86_64-unknown-linux-gnu' --label 'org.cross-rs.workspace_root=/home/runner/work/youki/youki' --tag localhost/cross-rs/cross-custom-youki:aarch64-unknown-linux-musl-3caa1 --build-arg 'CROSS_DEB_ARCH=musl-linux-arm64' --build-arg 'CROSS_BASE_IMAGE=ghcr.io/cross-rs/aarch64-unknown-linux-musl:main' --file /home/runner/work/youki/youki/cross/Dockerfile.musl --quiet --output 'type=docker' /home/runner/work/youki/youki` failed with exit status: 1

This change moves the logic previously provided by jorgeprendes420/apk-anywhere into Dockerfile.musl.

https://github.com/jprendes/apk-anywhere

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)
• Performance improvement
• Test updates
• CI/CD related changes
• Other (please describe): update Dockerfile

Testing

• Added new unit tests
• Added new integration tests
• Ran existing test suite
• Tested manually (please provide steps)

x86_64

$ CARGO=cross TARGET=x86_64-unknown-linux-musl just youki-release
$ file youki
youki: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), static-pie linked, stripped
$ readelf -h youki | grep Machine
  Machine:                           Advanced Micro Devices X86-64
$ ldd youki
        statically linked

aarch64

$ CARGO=cross TARGET=aarch64-unknown-linux-musl just youki-release
$ file youki
youki: ELF 64-bit LSB executable, ARM aarch64, version 1 (SYSV), statically linked, stripped
$ readelf -h youki | grep Machine
  Machine:                           AArch64
$ ldd youki
        not a dynamic executable

Related Issues

Fixes #

Additional Context

[utam0k]

Thanks!

[utam0k]

cc: @jprendes