### 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
}
					}
					ndevices.push_back(d);
				}
				ea->devices = ndevices;
				ea->devices_changed.set();
			}
		}
		uint64_t sleep = 200;
		uint64_t wait = 3000000;
		uint64_t time = OS::get_singleton()->get_ticks_usec();
		while (OS::get_singleton()->get_ticks_usec() - time < wait) {
			OS::get_singleton()->delay_usec(1000 * sleep);
			if (ea->quit_request.is_set()) {
				break;
			}
		}
	}
	if (EDITOR_GET("export/android/shutdown_adb_on_exit")) {
		String adb = get_adb_path();
		if (!FileAccess::exists(adb)) {
			return; 
		}
		List<String> args;
		args.push_back("kill-server");
		OS::get_singleton()->execute(adb, args);
	}
}
#endif
String EditorExportPlatformAndroid::get_project_name(const String &p_name) const {