Support building from `sdist` in a build action

Support building from `sdist` as a build action instead of `repository_rule`.

Things needed:
* [ ] A way to use a different `repository` rule that would not do any building with `pip`.
* [ ] Parsing the dependencies from `pyproject.toml` so that the `deps` field is populated at the repository time.
* [ ] A `pip` toolchain or something similar for building packages. Maybe we should have a `toolchain` for each build backend in the https://peps.python.org/pep-0621/
* [ ] A way to specify build dependencies see #1325.
* [ ] How do we build Python extensions?

Initial thoughts:
* It would be good to create an `sdist_archive` rule, which would download a given `sdist` by URL and then would parse `pyproject.toml`. If the `pyproject.toml` is not found or it is dynamic and requires Python to correctly infer the dependencies, we may need to fail at least in the first iteration.
* Using Python in the repository context is OK, but adds a lot of complication in the long run - we should attempt to limit its usage as much as possible.

At the moment I don't have time to work on this myself, but writing it down so that an issue for PEP621 based sdist building exists. Feel free to add thoughts here on possible design.