contracts: add hardhat task for whitelisting addresses

This PR adds a hardhat task for whitelisting addresses. It can be used like so:

```
$ npx hardhat whitelist --address 0x.. --use-ledger true --contracts-rpc-url https://...
```

.changeset/popular-carpets-applaud.md

+---
+'@eth-optimism/contracts': patch
+---
+
+Add hardhat task for whitelisting addresses

packages/contracts/hardhat.config.ts

@@ -16,6 +16,7 @@ import '@eth-optimism/hardhat-ovm'
 import './tasks/deploy'
 import './tasks/l2-gasprice'
 import './tasks/set-owner'
+import './tasks/whitelist'
 import 'hardhat-gas-reporter'
 
 // Load environment variables from .env

packages/contracts/tasks/whitelist.ts

+'use strict'
+
+import { ethers } from 'ethers'
+import { task } from 'hardhat/config'
+import * as types from 'hardhat/internal/core/params/argumentTypes'
+import { LedgerSigner } from '@ethersproject/hardware-wallets'
+import { getContractFactory } from '../src/contract-defs'
+import { predeploys } from '../src/predeploys'
+
+// Add accounts the the OVM_DeployerWhitelist
+// npx hardhat whitelist --address 0x..
+task('whitelist')
+  .addParam('address', 'Address to whitelist', undefined, types.string)
+  .addOptionalParam('transactionGasPrice', 'tx.gasPrice', undefined, types.int)
+  .addOptionalParam(
+    'useLedger',
+    'use a ledger for signing',
+    false,
+    types.boolean
+  )
+  .addOptionalParam(
+    'ledgerPath',
+    'ledger key derivation path',
+    ethers.utils.defaultPath,
+    types.string
+  )
+  .addOptionalParam(
+    'contractsRpcUrl',
+    'Sequencer HTTP Endpoint',
+    process.env.CONTRACTS_RPC_URL,
+    types.string
+  )
+  .addOptionalParam(
+    'contractsDeployerKey',
+    'Private Key',
+    process.env.CONTRACTS_DEPLOYER_KEY,
+    types.string
+  )
+  .addOptionalParam(
+    'contractAddress',
+    'Address of Ownable contract',
+    predeploys.OVM_DeployerWhitelist,
+    types.string
+  )
+  .setAction(async (args, hre: any) => {
+    const provider = new ethers.providers.JsonRpcProvider(args.contractsRpcUrl)
+    let signer: ethers.Signer
+    if (!args.useLedger) {
+      if (!args.contractsDeployerKey) {
+        throw new Error('Must pass --contracts-deployer-key')
+      }
+      signer = new ethers.Wallet(args.contractsDeployerKey).connect(provider)
+    } else {
+      signer = new LedgerSigner(provider, 'default', args.ledgerPath)
+    }
+
+    const deployerWhitelist = getContractFactory('OVM_DeployerWhitelist')
+      .connect(signer)
+      .attach(args.contractAddress)
+
+    const addr = await signer.getAddress()
+    console.log(`Using signer: ${addr}`)
+    let owner = await deployerWhitelist.owner()
+    console.log(`OVM_DeployerWhitelist owner: ${owner}`)
+
+    if (owner === '0x0000000000000000000000000000000000000000') {
+      console.log(`Initializing whitelist`)
+      const response = await deployerWhitelist.initialize(addr, false, {
+        gasPrice: args.transactionGasPrice,
+      })
+
+      const receipt = await response.wait()
+      console.log(`Initialized whitelist: ${receipt.transactionHash}`)
+      owner = await deployerWhitelist.owner()
+    }
+
+    if (addr !== owner) {
+      throw new Error(`Incorrect key. Owner ${owner}, Signer ${addr}`)
+    }
+
+    const res = await deployerWhitelist.setWhitelistedDeployer(
+      args.address,
+      true,
+      { gasPrice: args.transactionGasPrice }
+    )
+    await res.wait()
+    console.log(`Whitelisted ${args.address}`)
+  })