Improve url filter in ProxyController, less false positives

			$allowLocalAccess = $this->config->getAppValue('dav', 'webcalAllowLocalAccess', 'no');

			if ($allowLocalAccess !== 'yes') {

				$host = parse_url($url, PHP_URL_HOST);

				$host = strtolower(parse_url($url, PHP_URL_HOST));

				// remove brackets from IPv6 addresses

				if (strpos($host, '[') === 0 && substr($host, -1) === ']') {

					$host = substr($host, 1, -1);

				}

				if ($host === 'localhost' || substr($host, -6) === '.local' || substr($host, -10) === '.localhost' ||

					preg_match('/(^127\.)|(^192\.168\.)|(^10\.)|(^172\.1[6-9]\.)|(^172\.2[0-9]\.)|(^172\.3[0-1]\.)|(^::1$)|(^[fF][cCdD])/', $host)) {

					$this->logger->warning("Subscription $url was not refreshed because it violates local access rules");

				// Disallow localhost and local network

				if ($host === 'localhost' || substr($host, -6) === '.local' || substr($host, -10) === '.localhost') {

					$this->logger->warning("ProxyController: Subscription $url was not refreshed because it violates local access rules");

					$response = new JSONResponse([

						'message' => $this->l10n->t('URL violates local access rules'),

						'proxy_code' => 403

					], Http::STATUS_UNPROCESSABLE_ENTITY);

					return $response;

				}

				// Disallow hostname only

				if (substr_count($host, '.') === 0) {

					$this->logger->warning("ProxyController: Subscription $url was not refreshed because it violates local access rules");

					$response = new JSONResponse([

						'message' => $this->l10n->t('URL violates local access rules'),

						'proxy_code' => 403

					], Http::STATUS_UNPROCESSABLE_ENTITY);

					return $response;

				}

				if ((bool)filter_var($host, FILTER_VALIDATE_IP) && !filter_var($host, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)) {

					$this->logger->warning("ProxyController: Subscription $url was not refreshed because it violates local access rules");

					$response = new JSONResponse([

						'message' => $this->l10n->t('URL violates local access rules'),