[TS] Fix getFullyQualifiedName codegen for typescript (#7730)

#7451 caused getFullyQualifiedName to return a name with underscores,
not periods. Because the fully qualified name is a property of
FlatBuffers, not the language being codegen'd for, it should use
periods. Fixes #7564.

Co-authored-by: Derek Bailey <derekbailey@google.com>

src/idl_gen_ts.cpp

@@ -1898,7 +1898,10 @@ class TsGenerator : public BaseGenerator {
     if (parser_.opts.generate_name_strings) {
       GenDocComment(code_ptr);
       code += "static getFullyQualifiedName():string {\n";
-      code += "  return '" + WrapInNameSpace(struct_def) + "';\n";
+      code +=
+          "  return '" +
+          struct_def.defined_namespace->GetFullyQualifiedName(struct_def.name) +
+          "';\n";
       code += "}\n\n";
     }