Tweak wording of non-const traits used as const bounds

Use verbose suggestions and add additional labels/notes.

Add more test cases for stable/nightly and feature enabled/disabled.

compiler/rustc_hir_analysis/src/errors.rs

@@ -530,10 +530,16 @@ pub(crate) struct GenericArgsOnOverriddenImpl {
 #[diag(hir_analysis_const_impl_for_non_const_trait)]
 pub(crate) struct ConstImplForNonConstTrait {
     #[primary_span]
+    #[label]
     pub trait_ref_span: Span,
     pub trait_name: String,
-    #[suggestion(applicability = "machine-applicable", code = "#[const_trait]")]
+    #[suggestion(
+        applicability = "machine-applicable",
+        code = "#[const_trait] ",
+        style = "verbose"
+    )]
     pub local_trait_span: Option<Span>,
+    pub suggestion_pre: &'static str,
     #[note]
     pub marking: (),
     #[note(hir_analysis_adding)]
@@ -544,8 +550,19 @@ pub(crate) struct ConstImplForNonConstTrait {
 #[diag(hir_analysis_const_bound_for_non_const_trait)]
 pub(crate) struct ConstBoundForNonConstTrait {
     #[primary_span]
+    #[label]
     pub span: Span,
     pub modifier: &'static str,
+    #[note]
+    pub def_span: Option<Span>,
+    pub suggestion_pre: &'static str,
+    #[suggestion(
+        applicability = "machine-applicable",
+        code = "#[const_trait] ",
+        style = "verbose"
+    )]
+    pub suggestion: Option<Span>,
+    pub trait_name: String,
 }
 
 #[derive(Diagnostic)]