Convert `LOAD_ATTR_MODULE` to a constant where the module is already a constant

[markshannon]

Expressions like mod.attr, where mod is a module, are in almost all cases effectively constants.

We should optimize them as such.
We already treat the mod as a constant, so it is a relatively simple step to treat mod.attr as a constant.

Linked PRs

• GH-115651: Convert LOAD_MODULE_ATTR into LOAD_INLINE_CONST when the module is itself a constant. #115711

[gvanrossum]

Can this be closed now?