Port #[ignore] to the new attribute parsing infrastructure

Signed-off-by: Jonathan Brouwer <jonathantbrouwer@gmail.com>

compiler/rustc_attr_parsing/src/context.rs

@@ -37,6 +37,7 @@ use crate::attributes::semantics::MayDangleParser;
 use crate::attributes::stability::{
     BodyStabilityParser, ConstStabilityIndirectParser, ConstStabilityParser, StabilityParser,
 };
+use crate::attributes::test_attrs::IgnoreParser;
 use crate::attributes::traits::SkipDuringMethodDispatchParser;
 use crate::attributes::transparency::TransparencyParser;
 use crate::attributes::{AttributeParser as _, Combine, Single, WithoutArgs};
@@ -126,6 +127,7 @@ attribute_parsers!(
         // tidy-alphabetical-start
         Single<DeprecationParser>,
         Single<ExportNameParser>,
+        Single<IgnoreParser>,
         Single<InlineParser>,
         Single<LinkNameParser>,
         Single<LinkSectionParser>,