Submitting a PEP for the `{root:uri}`

[LecrisUT]

Would you consider formalizing the {root:uri} format as a PEP. I have found two use-cases where this would need a format PEP:

• build-system.requires for inter-dependent projects such as with hatchling and hatch. While this would not be able to be submitted to PyPI, it would still be useful for projects that are primarily distributed as git repos. We've added a similar parser for scikit-build-core because it can be very useful for compiled backends.
• dependency-groups for meta-projects. I have noticed that some usecases of the {roo:uri} is in meta-projects ^1 to guarantee that a synchronized version of dependencies is installed. But this can leave artifacts of the meta-project's dist-info, so dependency-groups should be a good alternative for it.

The issue in these cases though is that these are handled by the installers pip, uv etc. where hatchling logic cannot be injected, thus the proposal for formalizing this as a PEP.