ADD - create and emit Bug support for Diagnostics

UPDATE - migrate constant span_bug to translatable diagnostic.

compiler/rustc_codegen_ssa/src/errors.rs

@@ -585,6 +585,13 @@ pub struct ErroneousConstant {
     pub span: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_polymorphic_constant_too_generic)]
+pub struct PolymorphicConstantTooGeneric {
+    #[primary_span]
+    pub span: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(codegen_ssa_shuffle_indices_evaluation)]
 pub struct ShuffleIndicesEvaluation {