Rollup merge of #157305 - oli-obk:relaxed-bounds-maybe, r=fmease

Eagerly decide whether relaxed bounds are allowed or not

r? @davidtwco or @fmease

Previously introduced in rust-lang/rust#142693 by @fmease

I am trying to resolve https://github.com/rust-lang/rust/blob/d7986943e496ccb07987f4ad83c6f7033d725861/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs#L196, but then got into a rabbit hole somehwere.

I think this PR further unblocks resolving that FIXME, because it makes it easier to reason about whether we should be reporting an error about duplicate bounds or about relaxed bounds in general

Author: JonathanBrouwer