### 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
Ref<DirAccess> da_res = DirAccess::create(DirAccess::ACCESS_RESOURCES);
	
	if (da_res->dir_exists(APK_ASSETS_DIRECTORY)) {
		print_verbose("Clearing APK assets directory...");
		Ref<DirAccess> da_assets = DirAccess::open(APK_ASSETS_DIRECTORY);
		da_assets->erase_contents_recursive();
		da_res->remove(APK_ASSETS_DIRECTORY);
	}
	
	if (da_res->dir_exists(AAB_ASSETS_DIRECTORY)) {
		print_verbose("Clearing AAB assets directory...");
		Ref<DirAccess> da_assets = DirAccess::open(AAB_ASSETS_DIRECTORY);
		da_assets->erase_contents_recursive();
		da_res->remove(AAB_ASSETS_DIRECTORY);
	}
}
void EditorExportPlatformAndroid::_remove_copied_libs() {