WIP: This PR is probably not fully done and I am creating this so that the
contributors can collaborate.

I was thinking how we can start enabling the starlark implementation and roll
it out for more and more packages and for that we need more testing and this
test goes like following:

1. Call Simple API for top 500 packages.
2. Get the latest version wheel.
3. Use the Simple API to get the URL of the METADATA file only and its sha256.
4. Call the Python code to get the deps.
5. Parse METADATA file with Starlark and dump the requires_dist to a bzl
   file.
6. In a rules_testing test, run the Starlark implementation of deps parsing
   and compare it with the results we are getting for the Python
   implementation.

Once we have sufficient amount of testing done on all platforms our CI has, we
can think of how we can continue improving this. Some ideas:

• Cover more versions of the same wheel.
• Add particular wheels that are problematic.

This can hopefully be a tool to compare and debug problematic cases where we
need to understand what is going on and add a regression test to the Starlark
implementation.

Work towards #260, #2826