rebased: convert rustc_monomorphize errors to SessionDiagnostic

compiler/rustc_error_messages/locales/en-US/monomorphize.ftl

@@ -0,0 +1,19 @@
+monomorphize_recursion_limit =
+    reached the recursion limit while instantiating `{$shrunk}`
+    .note = `{$def_path_str}` defined here
+
+monomorphize_written_to_path = the full type name has been written to '{$path}'
+
+monomorphize_type_length_limit = reached the type-length limit while instantiating `{$shrunk}`
+
+monomorphize_consider_type_length_limit =
+    consider adding a `#![type_length_limit="{$type_length}"]` attribute to your crate
+
+monomorphize_fatal_error = {$error_message}
+
+monomorphize_unused_generic_params = item has unused generic parameters
+
+monomorphize_large_assignments =
+    moving {$size} bytes
+    .label = value moved from here
+    .note = The current maximum size is {$limit}, but it can be customized with the move_size_limit attribute: `#![move_size_limit = "..."]`

compiler/rustc_error_messages/src/lib.rs

@@ -39,6 +39,7 @@ fluent_messages! {
     expand => "../locales/en-US/expand.ftl",
     interface => "../locales/en-US/interface.ftl",
     lint => "../locales/en-US/lint.ftl",
+    monomorphize => "../locales/en-US/monomorphize.ftl",
     parser => "../locales/en-US/parser.ftl",
     passes => "../locales/en-US/passes.ftl",
     plugin_impl => "../locales/en-US/plugin_impl.ftl",