@OwnerUser @ProfileUser public static @NonNull String ensureAppFreeToLaunch(final Context context, final String pkg) {
		final DevicePolicies policies = new DevicePolicies(context);
		if (policies.invoke(DevicePolicyManager::isApplicationHidden, pkg)) {		// Hidden or not installed
			if (! policies.setApplicationHidden(pkg, false))
				if (! Apps.of(context).isInstalledInCurrentUser(pkg)) return "not_installed";	// Not installed in profile, just give up.
		}
		try {
			if (policies.isPackageSuspended(pkg))
				policies.invoke(DevicePolicyManager::setPackagesSuspended, new String[] { pkg }, false);
		} catch (final PackageManager.NameNotFoundException ignored) { return "not_found"; }
		return "";
	}
@return error information, or empty string for success.
shared/src/main/java/com/oasisfeng/island/engine/IslandManager.java