Include gdscript warning name in LSP message.

My initial attempt changed this in the gdscript code, which resulted in
a duplicate warning name in the builtin editor. We should just append
the warning name in the LSP instead.

This uses parens to match what is shown in the builtin editor.

modules/gdscript/language_server/gdscript_extend_parser.cpp

@@ -62,7 +62,7 @@ void ExtendGDScriptParser::update_diagnostics() {
 		const GDScriptWarning &warning = E->get();
 		lsp::Diagnostic diagnostic;
 		diagnostic.severity = lsp::DiagnosticSeverity::Warning;
-		diagnostic.message = warning.get_message();
+		diagnostic.message = "(" + warning.get_name() + "): " + warning.get_message();
 		diagnostic.source = "gdscript";
 		diagnostic.code = warning.code;
 		lsp::Range range;