### 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
return p_permissions.find("android.permission.MANAGE_EXTERNAL_STORAGE") != -1;
}
void EditorExportPlatformAndroid::_get_permissions(const Ref<EditorExportPreset> &p_preset, bool p_give_internet, Vector<String> &r_permissions) {
	const char **aperms = android_perms;
	while (*aperms) {
		bool enabled = p_preset->get("permissions/" + String(*aperms).to_lower());
		if (enabled) {
			r_permissions.push_back("android.permission." + String(*aperms));
		}
		aperms++;
	}
	PackedStringArray user_perms = p_preset->get("permissions/custom_permissions");
	for (int i = 0; i < user_perms.size(); i++) {
		String user_perm = user_perms[i].strip_edges();
		if (!user_perm.is_empty()) {
			r_permissions.push_back(user_perm);
		}
	}
	if (p_give_internet) {
		if (r_permissions.find("android.permission.INTERNET") == -1) {
			r_permissions.push_back("android.permission.INTERNET");
		}
	}
	int xr_mode_index = p_preset->get("xr_features/xr_mode");
	if (xr_mode_index == XR_MODE_OPENXR) {
		int hand_tracking_index = p_preset->get("xr_features/hand_tracking"); 
		if (hand_tracking_index > XR_HAND_TRACKING_NONE) {
			if (r_permissions.find("com.oculus.permission.HAND_TRACKING") == -1) {
				r_permissions.push_back("com.oculus.permission.HAND_TRACKING");