ENH Add micropip.uninstall()

[ryanking13]

Related: #51

Add micropip.uninstall() method, which uninstalls packages that are installed.

I used a quite simple approach for this compared to pip uninstall, since we only support installing wheels, and wheel metadata contain a list of files in the archive, so I just iterated through the list and removed them.

I didn't add a rollback feature if uninstall fails in this PR. I'm not sure it is worth it, but probably we can add it as a follow up.

• changelog

[rth]

Thanks @ryanking13 ! A couple of minor comments otherwise LGTM.

What would happen if we uninstall a package installed via loadPackage? If it also uninstalls it, we need to be sure loadPackage would be aware of it.

[ryanking13]

What would happen if we uninstall a package installed via loadPackage? If it also uninstalls it, we need to be sure loadPackage would be aware of it.

I think removing keys in loadedPackages does the job. Will add a test.

[ryanking13]

@rth Thanks for the review! I think I addressed all of your comments.

I changed the code a bit after your review (simplified how files are retrieved, and added tests), so I would appreciate it if you can review this one more time.

[rth]

One minor comment, otherwise LGTM. Thanks!