Rollup merge of #100831 - JhonnyBillM:migrate-symbol-mangling-to-diagnostics-structs, r=davidtwco

Migrate `symbol_mangling` module to new diagnostics structs

compiler/rustc_error_messages/src/lib.rs

@@ -54,6 +54,7 @@ fluent_messages! {
     ty_utils => "../locales/en-US/ty_utils.ftl",
     typeck => "../locales/en-US/typeck.ftl",
     mir_dataflow => "../locales/en-US/mir_dataflow.ftl",
+    symbol_mangling => "../locales/en-US/symbol_mangling.ftl",
 }
 
 pub use fluent_generated::{self as fluent, DEFAULT_LOCALE_RESOURCES};