Add MANTRA Chain Testnet (5887) configurations with icons (#7617)

* Add MANTRACHAIN Testnet (5887) configurations with icons

* fix(lint): code style issue

Author: freeelancer

_data/chains/eip155-5887.json

@@ -0,0 +1,28 @@
+{
+  "name": "MANTRACHAIN Testnet",
+  "chain": "Dukong",
+  "rpc": [
+    "https://evm.dukong.mantrachain.io",
+    "wss://evm.dukong.mantrachain.io/ws"
+  ],
+  "faucets": ["https://faucet.dukong.mantrachain.io"],
+  "nativeCurrency": {
+    "name": "OM",
+    "symbol": "OM",
+    "decimals": 18
+  },
+  "infoURL": "https://mantrachain.io",
+  "shortName": "dukong",
+  "chainId": 5887,
+  "networkId": 5887,
+  "slip44": 1,
+  "icon": "om",
+  "explorers": [
+    {
+      "name": "Dukong Explorer",
+      "url": "http://mantrascan.io",
+      "standard": "none",
+      "icon": "om"
+    }
+  ]
+}

_data/icons/om.json

@@ -0,0 +1,8 @@
+[
+  {
+    "url": "ipfs://bafkreiftgt747chqsw67a3jyklr52op5rozqmi3qnp4edwjcf2gxabwdnu",
+    "width": 120,
+    "height": 120,
+    "format": "png"
+  }
+]