Compress the uploaded pdf and save to database when user clicks upload

[AryenSinghal]

• Essentially, link the frontend with the backend.
• The uploaded pdf should be compressed for space efficiency. Make a follow up comment on this issue with your proposed compression algorithm before continuing.
• Save all note details, along with the pdf file, to the mongodb database
• The database schema in the drive folder and TritonScriptAPI.md in the repo will come in handy