Add Base testnet chain definition (ethereum-lists#2318)

* Add Base testnet chain definition

* Add explorers and prettier format

---------

Co-authored-by: Andrew Flockhart <[email protected]>

Author: barmstrong

_data/chains/eip155-84531.json

@@ -0,0 +1,27 @@
+{
+  "name": "Base Goerli Testnet",
+  "chain": "ETH",
+  "rpc": ["https://goerli.base.org"],
+  "faucets": ["https://www.coinbase.com/faucets/base-ethereum-goerli-faucet"],
+  "nativeCurrency": {
+    "name": "Goerli Ether",
+    "symbol": "ETH",
+    "decimals": 18
+  },
+  "infoURL": "https://base.org",
+  "shortName": "basegor",
+  "chainId": 84531,
+  "networkId": 84531,
+  "explorers": [
+    {
+      "name": "basescan",
+      "url": "https://goerli.basescan.org",
+      "standard": "none"
+    },
+    {
+      "name": "basescout",
+      "url": "https://base-goerli.blockscout.com",
+      "standard": "none"
+    }
+  ]
+}