Add missing #[rustc_lint_diagnostics] attributes.

Prior to the previous commit, `#[rust_lint_diagnostics]` attributes
could only be used on methods with an `impl Into<{D,Subd}iagMessage>`
parameter. But there are many other nearby diagnostic methods (e.g.
`Diag::span`) that don't take such a parameter and should have the
attribute.

This commit adds the missing attribute to these `Diag` methods. This
requires adding some missing
`#[allow(rustc::diagnostic_outside_of_impl)]` markers at call sites to
these methods.

compiler/rustc_passes/src/check_attr.rs

@@ -2330,6 +2330,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
 
             let hir_sig = tcx.hir().fn_sig_by_hir_id(hir_id);
             if let Some(hir_sig) = hir_sig {
+                #[allow(rustc::diagnostic_outside_of_impl)] // FIXME
                 match terr {
                     TypeError::ArgumentMutability(idx) | TypeError::ArgumentSorts(_, idx) => {
                         if let Some(ty) = hir_sig.decl.inputs.get(idx) {