feat(cli): add blockExplorers option on registry init (#4149)

### Description

- adds blockExplorers option on registry init

### Drive-by changes

- none

### Related issues

- none

### Backward compatibility

- yes

### Testing

- manual

.changeset/great-candles-battle.md

@@ -0,0 +1,5 @@
+---
+'@hyperlane-xyz/cli': minor
+---
+
+Adds blockExplorers option on registry init.

typescript/cli/src/config/chain.ts

@@ -1,10 +1,11 @@
-import { confirm, input } from '@inquirer/prompts';
+import { confirm, input, select } from '@inquirer/prompts';
 import { ethers } from 'ethers';
 import { stringify as yamlStringify } from 'yaml';
 
 import {
   ChainMetadata,
   ChainMetadataSchema,
+  ExplorerFamily,
   ZChainName,
 } from '@hyperlane-xyz/sdk';
 import { ProtocolType } from '@hyperlane-xyz/utils';
@@ -89,6 +90,8 @@ export async function createChainConfig({
     rpcUrls: [{ http: rpcUrl }],
   };
 
+  await addBlockExplorerConfig(metadata);
+
   await addBlockOrGasConfig(metadata);
 
   await addNativeTokenConfig(metadata);
@@ -111,6 +114,42 @@ export async function createChainConfig({
   }
 }
 
+async function addBlockExplorerConfig(metadata: ChainMetadata): Promise<void> {
+  const wantBlockExplorerConfig = await confirm({
+    default: false,
+    message: 'Do you want to add a block explorer config for this chain',
+  });
+  if (wantBlockExplorerConfig) {
+    const name = await input({
+      message: 'Enter a human readable name for the explorer:',
+    });
+    const url = await input({
+      message: 'Enter the base URL for the explorer:',
+    });
+    const apiUrl = await input({
+      message: 'Enter the base URL for requests to the explorer API:',
+    });
+    const family = (await select({
+      message: 'Select the type (family) of block explorer:',
+      choices: Object.entries(ExplorerFamily).map(([_, value]) => ({ value })),
+      pageSize: 10,
+    })) as ExplorerFamily;
+    const apiKey =
+      (await input({
+        message:
+          "Optional: Provide an API key for the explorer, or press 'enter' to skip. Please be sure to remove this field if you intend to add your config to the Hyperlane registry:",
+      })) ?? undefined;
+    metadata.blockExplorers = [];
+    metadata.blockExplorers[0] = {
+      name,
+      url,
+      apiUrl,
+      family,
+    };
+    if (apiKey) metadata.blockExplorers[0].apiKey = apiKey;
+  }
+}
+
 async function addBlockOrGasConfig(metadata: ChainMetadata): Promise<void> {
   const wantBlockOrGasConfig = await confirm({
     default: false,