Migrate most of rustc_builtin_macros to diagnostic impls

Co-authored-by: Joe ST <joe@fbstj.net>
Co-authored-by: Michael Goulet <michael@errs.io>

compiler/rustc_errors/src/lib.rs

@@ -383,7 +383,9 @@ pub use diagnostic::{
     DiagnosticStyledString, IntoDiagnosticArg, SubDiagnostic,
 };
 pub use diagnostic_builder::{DiagnosticBuilder, EmissionGuarantee, Noted};
-pub use diagnostic_impls::{DiagnosticArgFromDisplay, DiagnosticSymbolList};
+pub use diagnostic_impls::{
+    DiagnosticArgFromDisplay, DiagnosticSymbolList, LabelKind, SingleLabelManySpans,
+};
 use std::backtrace::Backtrace;
 
 /// A handler deals with errors and other compiler output.