gh-117953: Track All Extension Modules

[ericsnowcurrently]

When an extension module is loaded, the init function is looked up and run. If that doesn't fail then the module is "fixed up", which includes adding its PyModuleDef to a global mapping that is used if the module is re-loaded. However, that has not applied to multi-phase init modules. Adding those modules to the global mapping would identify that we already loaded the module (or at least tried), as well as the module's kind. That's especially useful for a follow up PR I have planned.

(This is based on gh-118116. For the diff, see my track-all-ext-modules branch.)

• Issue: Single-Phase Init Extension Module Init Functions Still Run in Isolated Interpreters #117953