Support ARM64/amd64/ multi-arch images

[egk10]

As CSM Lido operator running on SSV , and to improve redundancy, I decided to invest on Orange Pi 5 Plus 32Gb Ram and got frustrated when eth-docker and SSV are not able to run SSV on ARM.

Right now SSV doesn't use a locally built image at all, and so also doesn't support source building

SOLUTION:
support amd64/arm64 multi-arch images

Alternative
Eth-docker to learn how to source-build SSV images when on arm64
Dockerfile.source for SSV creating a minimal Dockerfile.binary with just a FROM line, so that SSV uses locally built images always.