[AssumptionCache] Track GlobalValues as affected values. (#65425)

Fixes a corner case of the analysis: previously GlobalValues could be
affected by assumptions, but were not tracked within AffectedValues.
This patch allows assumptions which affect a given GlobalValue to be
looked up via `assumptionsFor()`.

A small update to llvm/test/Analysis/ScalarEvolution/ranges.ll was
necessary due to knowledge about a global value now being propagated
from AssumptionCache -> ValueTracking -> ScalarEvolution.