Add option to parallel() to allow user to select which tasks to run

[NWylynko]

export default scripts({
  build: parallel([
    command({
      run: "pnpm build",
      cwd: "next"
    }, 'Build the Website'),
    command({
      run: "pnpm build",
      cwd: "expo"
    }, 'Build the mobile app'),
    command({
      run: "pnpm build",
      cwd: "fastify"
    }, 'Build the backend server'),
  ], 'Build the modules', {
    optional: true
  })
})

With a scripts.ts like this, it would cool if it asked the user which steps to run in parallel, for example the user might only want to build the mobile app and backend as thats all they are working on.

[NWylynko]

A new function instead called something like optionalParallel or promptParallel could make more sense and give the user more control.

export default scripts({
  build: optionalParallel({
    website: command({
      run: "pnpm build",
      cwd: "next"
    }, 'Build the Website'),
    app: command({
      run: "pnpm build",
      cwd: "expo"
    }, 'Build the mobile app'),
    server: command({
      run: "pnpm build",
      cwd: "fastify"
    }, 'Build the backend server'),
  }, 'Build the modules', {
    prompt: 'Which modules would you like to build?',
    default: ['website', 'app', 'server']
  })
})