Add a public API method for searching cross-build environments

[agriyakhetarpal]

Projects like cibuildwheel are currently calling

xbuildenvs_info_str = call(
        "pyodide",
        "xbuildenv",
        "search",
        "--json",
        "--all",
        env=env,
        cwd=CIBW_CACHE_PATH,
        capture_stdout=True,
    ).strip()

in pypa/cibuildwheel#2002, which was first added in #26.

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@hoodmane says:

Maybe we should add a Python API for this to pyodide-build.

@agriyakhetarpal says:

Yes, we have a MetadataView class that's used for this: https://github.com/pyodide/pyodide-build/blob/7126c5f1bd56ed7f40ce29cbcbe588267a42434c/pyodide_build/views.py

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See pypa/cibuildwheel#2002 (comment)

[agriyakhetarpal]

What should this look like? Does something like the following work?

pyodide_build.xbuildenv.CrossBuildEnvManager.search(json=False, all=False)

I think it could, as we already have list_versions, _find_remote_release, and we can just reuse the logic from MetadataView for printing the table.

[ryanking13]

Thanks for the suggestion. Currently, all pyodide-build's APIs do not assume that they will be used by external projects, so they do not guarantee backward compatibility. So I'm a little bit cautious about providing an API like that in the sense that we are going to have to be more careful about making changes in the future. Anyways, I'm not against this proposal, and let's think about what we can do to help projects like cibuildwheel make better use of pyodide-build.