HIR analysis: Remove unnecessary abstraction over list of clauses
`rustc_hir_analysis::bounds::Bounds` with its methods is nowadays a paper-thin wrapper around `Vec<(Clause, Span)>`s and `Vec::push` essentially.
Its existence slightly annoyed me (and I keep opening its corresp. file instead of the identically named `bounds.rs` in `hir_ty_lowering/` that I actually want most of the time :P).
Opening to check if you agree with inlining it.
r? compiler-errors or reassign
2a25a16c57