feat: Cache Prepared Data and implement Dataset class

[tsunrise]

Closes: #4

• Add scripts to prepare data and save to cache
  
• Run those scripts and host prepared data on the web
• Add logic to download prepared data from the web
• Implement Dataset class to abstract the logic

Demo Commands:

• Train:

python .\main.py --n_files 50 --n_epochs 200

• predict:

python .\predict_stream.py --load_checkpoint .project_data\snapshots\<your trained model>

[violetyao]

LGTM. Thank you so much!

[YixinLiu030]

LGTM and thank you!