Replace autoconf configure.ac with a Python-based configure system

[nascheme]

See draft copy of PEP. This will be posted and discussed on DPO.

Linked PRs

• GH-148112: Add configure.py, a configure.ac replacement #146034

[picnixz]

PEPs should be opened as a Discuss Thread and PR against python/peps instead. We only open issues here once the PEP has been accepted. Please do not bypass that process.

[picnixz]

I am going to close this one for now but we can reuse it later. Please make it a DPO thread and open any draft PEP as a DPO thread first (I am not even sure we encourage draft PEPs to be submitted without a public discussion).

[nascheme]

I don't feel I'm bypassing the PEP process. I will be posting to discuss.python.org, after getting a PEP number assigned. I was only using the Github issue to get some feedback from a smaller set of people, before I announce the PEP more broadly. I guess I'll use somewhere else to post it and get feedback.