Add a --keep-going option to the pyodide build CLI

[agriyakhetarpal]

Description

This issue proposes the addition of a --keep-going option to enable building recipes until completion and listing failed recipes at the end of the build procedure – this is so that the procedure doesn't come to a halt once one recipe fails to build.

Motivation

This came about in pyodide/pyodide#4925 when updating quite a few recipes at once

[agriyakhetarpal]

I should be able to take a look at this myself in a while – and also come back to my other open PR :)

[hoodmane]

I made an attempt at this a while back. See also
pyodide/pyodide#3249
pyodide/pyodide#4491

[ryanking13]

Yes, it would be useful to have such flag. It won't be useful for non-maintainers so I am +1 for adding it as an hidden flag.

[hoodmane]

Personally I would prefer not to hide it. I think maintainers are the heaviest users of the CLI and it is annoying to have to grep the codebase. Others can either use it or not. The description will be simple enough.

[ryanking13]

Sure, that's fine with me.