Feat/multiple download performance testing

[jacob50231]

New Features

• Enhanced Asynchronous Multiple File Download: Introduces a high-performance async_download_multiple method utilizing hybrid concurrency (multiprocessing + asyncio) with memory-efficient queue-based management
• New CLI Command: Adds gen3 download-multiple-async command with advanced options like resuming downloads (--skip-completed), flexible filename formatting, and progress bars
• Performance Testing Suite: Added comprehensive benchmarking framework comparing the new implementation against CDIS Data Client for download speed, memory usage, and concurrency efficiency

Dependency updates
Updated fastavro from 1.8.4 to 1.11.1
Updated pypfb to include extras: pypfb = {extras = ["gen3"], version = "^0.5.33"}
Updated importlib-metadata from 8.5.0 to 4.13.0