Port several trait/coherence-related attributes the new attribute system Part of rust-lang/rust#131229 This ports: - `#[const_trait]` - `#[rustc_deny_explicit_impl]` - `#[rustc_do_not_implement_via_object]` - `#[rustc_coinductive]` - `#[type_const]` - `#[rustc_specialization_trait]` - `#[rustc_unsafe_specialization_marker]` - `#[marker]` - `#[fundamental]` - `#[rustc_paren_sugar]` - `#[rustc_allow_incoherent_impl]` - `#[rustc_coherence_is_core]` This also changes `#[marker]` to error on duplicates instead of warning. cc rust-lang/rust#142838, but I don't think it matters too much, since it's unstable. r? ``@oli-obk``