WIP: Python no runtime deps at build time

[adisbladis]

Description of changes

Removes dependency propagation from buildPythonPackage when a runtime dependency is passed via dependencies.

Please don't actually review the code yet. This a a very WIP, very draft PoC & should be considered a demo for #272178.
This also includes the commits from #271597.
Only the commits prefixed with WIP: are a part of this.

python3Packages.foo

Depending on a Python package like this will break:

stdenv.mkDerivation {
  propagatedBuildInputs = [ python3Packages.requests ];
}

You will instead need to:

stdenv.mkDerivation {
  propagatedBuildInputs = python3Packages.requiredPythonModules [ python3Packages.requests ];
}

This is because dependencies are no longer build-time propagated, so the full dependency graph calculation needs to happen in the Nix evaluator.

python3Packages.buildPythonPackage vs python3Packages.buildPythonApplication

• buildPythonPackage is for building a Python package without dependency propagation
• buildPythonApplication is for building application bundles. This internally calls buildPythonPackage, and also creates a wrapper derivation that takes care of calling requiredPythonModules.

All Python applications which has runnable binaries now needs to either be:

• Created using buildPythonApplication
• Converted from a Python module using toPythonApplication

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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