build: support local arm64 and amd64 image

[heidongxianhua]

Fixes #12750

Motivation

Modifications

Verification

[Joibel]

I'd like by default not to build both images. In #12750 I asked for:

We'd accept a PR for formalizing this if you want to do it, so long as it only built for the "same as your machine" in the default case. You could set an environment variable to override this behavior.

[Joibel]

I would also like there to be a line in the documentation about this feature, documenting both single and multiple platform builds.

[heidongxianhua]

sorry to delay, and now I have fixed it and give a case in docs to introduce how to use it. @Joibel

[Joibel]

Thanks.

I'd prefer an approach that didn't assume amd64 in non arm cases, but this is good enough for now and can iterate later.

[Joibel]

@agilgur5, could you take another look please.

[agilgur5]

Some small adjustments in-line below

I'd prefer an approach that didn't assume amd64 in non arm cases, but this is good enough for now and can iterate later.

Agreed

[agilgur5]

LGTM