Rollup merge of #128020 - compiler-errors:nlb-no-const, r=BoxyUwU

Just totally fully deny late-bound consts

Kinda don't care about supporting this until we have where clauses on binders. They're super busted and should be reworked in due time, and they are approximately 100% useless until then 😸

Fixes #127970
Fixes #127009

r? ``@BoxyUwU``