Adds "cocoapods-installer" option

Summary:
Adds "cocoapods-installer" option to "setup-dev" command to decide who CocoaPods will be installed on the macOS host system.

The options are "gem" and "homebrew".

## Gem

```
npx torchlive-cli setup-dev --cocoapods-installer=gem
```

## Homebrew

```
npx torchlive-cli setup-dev --cocoapods-installer=homebrew
```

Note: the option will be used for the GitHub Action CI that tests the setup-dev command

## Test

Tested in forked repo: https://github.com/raedle/live/runs/4576829417

Reviewed By: liuyinglao

Differential Revision: D33229271

fbshipit-source-id: 2019748854c25c2f5a71db334040e116e56ef9a0

torchlive-cli/src/cli-commands/SetUpDev.ts

@@ -23,6 +23,7 @@ import {runTasks} from '../utils/TaskUtils';
 
 type SetupDevOptions = {
   yes: boolean;
+  cocoapodsInstaller: string | undefined;
 };
 
 const setUpDev = async (options: SetupDevOptions): Promise<void> => {
@@ -47,5 +48,9 @@ export function makeSetUpDevCommand() {
   return new Command('setup-dev')
     .description('set up development dependencies')
     .option('-y, --yes', 'Accept all questions')
+    .option(
+      '--cocoapods-installer [installer]',
+      'CocoaPods Package Installer (gem or homebrew)',
+    )
     .action(setUpDev);
 }

torchlive-cli/src/installers/ios/CocoaPodsInstaller.ts

@@ -45,21 +45,36 @@ export default class CocoaPodsInstaller implements ICommandInstallerTask {
   }
 
   async run(context: TaskContext): Promise<void> {
-    const source = await context.task.prompt<string>([
-      {
-        type: 'Select',
-        name: 'source',
-        message:
-          "CocoaPods (https://cocoapods.org/) is not installed. It's necessary for iOS project to run correctly. Do you want to install it?",
-        choices: ['Yes, with gem (may require sudo)', 'Yes,‎ with‎ Homebrew'],
-      },
-    ]);
+    let {cocoapodsInstaller} = context.ctx;
+    if (cocoapodsInstaller == null) {
+      cocoapodsInstaller = await context.task.prompt<string>([
+        {
+          type: 'Select',
+          name: 'source',
+          message:
+            "CocoaPods (https://cocoapods.org/) is not installed. It's necessary for iOS project to run correctly. Do you want to install it?",
+          choices: [
+            {
+              name: 'gem',
+              message: 'Yes, with gem (may require sudo)',
+            },
+            {
+              name: 'homebrew',
+              message: 'Yes,‎ with‎ Homebrew',
+            },
+          ],
+        },
+      ]);
+    }
 
-    if (source === 'Yes, with gem (may require sudo)') {
+    if (cocoapodsInstaller === 'gem') {
       return await this.installWithGem(context);
-    } else {
+    } else if (cocoapodsInstaller === 'homebrew') {
       return await this.installWithHomebrew(context);
     }
+    throw new Error(
+      `${cocoapodsInstaller} is not a valid option to install CocoaPods`,
+    );
   }
 
   private async installWithGem(context: TaskContext): Promise<void> {