Add solhint to contracts package

packages/contracts/.solhint.json

+{
+  "extends": "solhint:recommended",
+  "plugins": [],
+    "rules": {
+
+    }
+}

packages/contracts/.solhintignore

+node_modules

packages/contracts/package.json

@@ -37,6 +37,7 @@
     "posttest:slither": "rm -f @openzeppelin && rm -f @ens && rm -f hardhat",
     "lint:check": "eslint .",
     "lint:fix": "yarn lint:check --fix",
+    "lint:contracts": "yarn solhint contracts/optimistic-ethereum/**/*.sol",
     "clean": "rm -rf ./dist ./artifacts ./artifacts-ovm ./cache ./cache-ovm ./tsconfig.build.tsbuildinfo",
     "deploy": "ts-node \"./bin/deploy.ts\" && yarn generate-markdown",
     "serve": "./bin/serve_dump.sh",
@@ -105,6 +106,7 @@
     "lint-staged": "11.0.0",
     "random-bytes-seed": "^1.0.3",
     "rlp": "^2.2.6",
+    "solhint": "^3.3.6",
     "solidity-coverage": "^0.7.16",
     "ts-generator": "0.0.8",
     "ts-node": "^9.1.1",