various: add rustc_lint_diagnostics to diag fns

The `rustc_lint_diagnostics` attribute is used by the diagnostic
translation/struct migration lints to identify calls where
non-translatable diagnostics or diagnostics outwith impls are being
created. Any function used in creating a diagnostic should be annotated
with this attribute so this commit adds the attribute to many more
functions.

Signed-off-by: David Wood <david.wood@huawei.com>

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -357,6 +357,7 @@ impl<'a> DerefMut for SnapshotParser<'a> {
 }
 
 impl<'a> Parser<'a> {
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub(super) fn span_err<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -365,6 +366,7 @@ impl<'a> Parser<'a> {
         err.span_err(sp, self.diagnostic())
     }
 
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_span_err<S: Into<MultiSpan>>(
         &self,
         sp: S,