Refactor for libmamba v2 (WIP)

[jaimergp]

Description

A WIP branch of the refactors enabled by libmamba v2. Supersedes #414.

Progress:

• Refactor index helpers
• Refactor repoquery
• Refactor solver
• Refactor conflict reports
• Pass all tests
• Polish and clean up

Checklist - did you ...

• Add a file to the news directory (using the template) for the next release's release notes?
• Add / update necessary tests?
• Add / update outdated documentation?

[jaimergp]

pre-commit.ci autofix

[jaimergp]

Well, well, we are down to one failing test in Unix:

tests/core/test_solve.py::test_channel_priority_churn_minimized[libmamba]

Everything else is passing with the help of conda/conda#13784.

Windows has a couple of extra issues but nothing major. To be investigated.

[jaimergp]

I looked into the Windows errors and while I can reproduce the pytest errors, equivalent exercises without pytest do pass locally 🤷

• tests/test_channels.py::test_mirrors_do_not_leak_channels
• tests/test_workarounds.py::test_ctrl_c: I can Ctrl+C twice to cancel the job. But I don't get the usual Python "KeyboardInterrupt" now. See v2: Ctrl+C / SIGINT / KeyboardInterrupt handling not working mamba-org/mamba#3271 & Hotfix to allow Ctrl+C in python scipts mamba-org/mamba#3285.