Updated code with greeting support

Update date and time to UTC format

Implementation for Google drive is done. Now it is working fine, except need a new function that can delete the chunks if a document is removed from google drive.

Enhanced the support for the excel file and added endpoint to have optimized vector store and Rag for the Excel.

Working chat with context and history

Setup completed

Commit chatbot chnages

Updated Knowledge base with Upload, get and delete endpoints

Update knowledge upload api and linked chromadb to mongodb

Refactoring code