### Godot version

3.5.1.stable, v4.0.beta.custom_build [0a87ead64]

### System information

Ubuntu 22.04.1

### Issue description

For example, if project has name "300spartans", we can't enter the "org.godotengine.300spartans" to "Unique Name" field. We get the error "Invalid package name: A digit cannot be the first character in a package segment". But , if we enter "org.godotengine.$genname", there will be no error message. When exporting, the name will be set as "org.godotengine.spartans" without "300" in beginning, but user will not be informed about it. I think, it is not very good. It may not be worth making changes to the source code, but mention it in the documentation.

### Steps to reproduce

See issue description.

### Minimal reproduction project

N/A
print_line("Installing to device (please wait...): " + devices[p_device].name);
	if (ep.step(TTR("Installing to device, please wait..."), 2)) {
		CLEANUP_AND_RETURN(ERR_SKIP);
	}
	args.clear();
	args.push_back("-s");
	args.push_back(devices[p_device].id);
	args.push_back("install");
	args.push_back("-r");
	args.push_back(tmp_export_path);
	output.clear();
	err = OS::get_singleton()->execute(adb, args, &output, &rv, true);
	print_verbose(output);
	if (err || rv != 0) {
		add_message(EXPORT_MESSAGE_ERROR, TTR("Run"), vformat(TTR("Could not install to device: %s"), output));
		CLEANUP_AND_RETURN(ERR_CANT_CREATE);
	}
	if (use_remote) {
		if (use_reverse) {
			static const char *const msg = "--- Device API >= 21; debugging over USB ---";
			EditorNode::get_singleton()->get_log()->add_message(msg, EditorLog::MSG_TYPE_EDITOR);
			print_line(String(msg).to_upper());
			args.clear();
			args.push_back("-s");
			args.push_back(devices[p_device].id);
			args.push_back("reverse");
			args.push_back("--remove-all");
			output.clear();
			OS::get_singleton()->execute(adb, args, &output, &rv, true);
			print_verbose(output);