Execute posy built-frontend to build the wheel.

[Tim de Jager]

When we have access to venv's from #78 we can then use the posy build-frontend to actually build the wheel from an Sdist.

To do this:

During resolution:

• Use the information from the Sdist pyproject to get the build backend and requirements
• Resolve an environment and install this into a #78 venv.
• Run the posy frontend to get metadata using the prepare_metadata_for_build_wheel hook and associate this metadata with the artifact. Probably need to modify the frontend to suit our use-case.

During installation

• Run the posy frontend to build the wheel using the build_wheel function to actually build and save it in the wheel cache #79

Important note is that the prepare_metadata_for_build_wheel need not exist so we need to differentiate between this in some way, if it was build or if it has just created the metadata.

[Tim de Jager]

Intial PR is here: #84

[Tim de Jager]

Closed by #84