feat: Add Arbitrum URL for Sentinel (#517)

Signed-off-by: dan437 <80175477+dan437@users.noreply.github.com>

Author: dan437

src/constants.ts

@@ -9,6 +9,7 @@ export const SENTINEL_API_BASE_URL_MAP: SentinelApiBaseUrlMap = {
   1: 'https://tx-sentinel-ethereum-mainnet.api.cx.metamask.io',
   56: 'https://tx-sentinel-bsc-mainnet.api.cx.metamask.io',
   8453: 'https://tx-sentinel-base-mainnet.api.cx.metamask.io',
+  42161: 'https://tx-sentinel-arbitrum-mainnet.api.cx.metamask.io',
   11155111: 'https://tx-sentinel-ethereum-sepolia.api.cx.metamask.io',
 };