Add cli suppport ui.batch() for concurrent task execution

[k1rana]

The Problem

The current this.ui.tasks() works perfectly for defined, sequential steps (scaffold -> install -> build). However, using it for dynamic lists (e.g., processing 50 files) is painful because:

1. We have to manually loop and chain .add().
2. It enforces sequential execution, which is a bottleneck for independent items.

The Proposal

I propose adding a new method (e.g., ui.batch or ui.parallel) specifically designed for processing arrays of data with concurrency.

This method would exist alongside the current ui.tasks(), so no breaking changes are needed for existing commands.

Proposed API

This new method would accept an array of task definitions (similar to listr2 structure) and an options object for concurrency/workers.

const files = ['file1.png', 'file2.png', 'file3.png', 'file4.png']

// New method: ui.batch(tasksArray, options)
await this.ui.batch(
  files.map(file => ({
    title: `Optimizing ${file}`,
    // The task logic
    run: async () => {
       await optimize(file)
    }
  })), 
  { 
    concurrency: 5 // Run 5 items in parallel
  }
)