Support source rewriting

[yajo]

The context of this issue is that I'd want to fix odoo/upgrade-util#190 (install odoo-upgrade, which uses hatchling, in editable mode). According to my experience with the great team behind that project, I guess that if I propose to rename the folder src to odoo/upgrade, they'll most likely answer no.

The error that you can see in that issue was intruduced in #407 and points to lack of support in pfmoore/editables#20. It happens because of this configuration.

However, pfmoore/editables#20 seems fixed upstream. editables docs seem to explain how to do that renaming.

So, maybe it's time to lift the block introduced in #407 and actually allow editable installation on renamed packages?

Thanks!

@moduon MT-3426