Rollup merge of #100651 - nidnogg:diagnostics_migration_expand_transcribe, r=davidtwco

Migrations for rustc_expand transcribe.rs

This PR includes some migrations to the new diagnostics API for the `rustc_expand` module.
r? ```@davidtwco```

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

@@ -3,3 +3,20 @@ expand_explain_doc_comment_outer =
 
 expand_explain_doc_comment_inner =
     inner doc comments expand to `#![doc = "..."]`, which is what this macro attempted to match
+
+expand_expr_repeat_no_syntax_vars = 
+    attempted to repeat an expression containing no syntax variables matched as repeating at this depth
+
+expand_must_repeat_once = 
+    this must repeat at least once
+
+expand_count_repetition_misplaced =
+    `count` can not be placed inside the inner-most repetition
+
+expand_meta_var_expr_unrecognized_var =
+    variable `{$key}` is not recognized in meta-variable expression
+
+expand_var_still_repeating =
+    variable '{$ident}' is still repeating at this depth
+
+expand_meta_var_dif_seq_matchers = {$msg}