src: add missing option parser template for the DebugOptionsParser

This allows embedders to run `node::options_parser::Parse` for a
`node::DebugOptions`.

PR-URL: #28543
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Eugene Ostroukhov <eostroukhov@google.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

src/node_options.cc

@@ -226,6 +226,17 @@ class PerProcessOptionsParser : public OptionsParser<PerProcessOptions> {
 #if HAVE_INSPECTOR
 const DebugOptionsParser _dop_instance{};
 const EnvironmentOptionsParser _eop_instance{_dop_instance};
+
+// This Parse is not dead code. It is used by embedders (e.g., Electron).
+template <>
+void Parse(
+  StringVector* const args, StringVector* const exec_args,
+  StringVector* const v8_args,
+  DebugOptions* const options,
+  OptionEnvvarSettings required_env_settings, StringVector* const errors) {
+  _dop_instance.Parse(
+    args, exec_args, v8_args, options, required_env_settings, errors);
+}
 #else
 const EnvironmentOptionsParser _eop_instance{};
 #endif  // HAVE_INSPECTOR