Convert from sdist

[analog-cbarber]

Support conversion from sdist files to conda packages.

The python source distribution file format is described here:

https://packaging.python.org/en/latest/specifications/source-distribution-format/

The PKG-INFO file in the distribution has metadata in the same format as the METADATA
file in a wheel (not sure if there are any differences).

Any script entrypoints must be found in the pyproject.toml file.

[analog-cbarber]

It isn't entirely clear from the documentation, but I think you can build a wheel from the sdist using pip wheel *.tar.gz,
so we could just build a wheel and go from there.

[analog-cbarber]

We would want to make sure to error out if the sdist is not pure python. Would --no-binary :all: do this or does that only affect dependencies?