Auto merge of #106976 - tmiasko:borrowck-lazy-dominators, r=cjgillot

Lazy dominator tree construction in borrowck

Motivated by the observation that sometimes constructed dominator tree was never queried.

diff --cc compiler/rustc_borrowck/src/lib.rs
Simple merge

diff --cc compiler/rustc_data_structures/src/graph/dominators/mod.rs
Simple merge