Add aarch64-native QEMU emulators

[MementoRC]

Problem

With ubuntu-24.04-arm runners in use (build_platform: {linux_ppc64le: linux_aarch64}), an image can run natively on aarch64 and be asked to emulate ppc64le. The bundled emulators cannot be executed there.

Measured on the published image:

$ docker image inspect quay.io/condaforge/linux-anvil-aarch64:alma10 --format '{{.Os}}/{{.Architecture}}'
linux/arm64
$ file qemu-ppc64le-static      # copied out of that image
ELF 64-bit LSB pie executable, x86-64, static-pie linked, stripped

Change

Fedora publishes aarch64-host builds at the version already pinned here.
Fetch those as well, under an -aarch64 suffix. Verified ARM-native:

qemu-ppc64le-static-aarch64: ELF 64-bit LSB pie executable,
ARM aarch64, static-pie linked, stripped

• Extraction streams to an explicitly named file instead of extracting in place.
• linux-anvil-cuda mirrors its own narrower target subset.

Context

Motivated by conda-forge/conda-smithy#2688. With this, smithy's aarch64 branch can register binfmt handlers with the same OC flags and image-supplied interpreters as x86_64, instead of relying on tonistiigi/binfmt.

Open questions

• Keep linux-anvil-cuda in scope, or limit to linux-anvil?
• Is the -aarch64 suffix ok, or host-arch subdirectories?
• Bump the pinned qemu from 8.2.8 separately? 11.x has ppc64le fixes relevant to emulated test suites.