Adding Backend requirements

[AthulyaMS]

This PR includes

• FastAPI Application Setup
• Database Connection - get-db and Database Models
• JWT Authentication (Password Hashing,JWT Token Creation)
• User Management APIs
• File Upload and Processing
• ZIP File Handling
• Added Transcribe API
• Addded GET Status
• Added PUT languages ,chapter approve ,text modification
• Added convert to Speech and download
• Added input and output in different folders
• Added project in a structure

[KetanKBaboo]

Note :-
In routers.py file, "approved" keys in the response of get_user_projects api("/projects/") are currently commented. Please do check if it's needed as per SRS requirement.

[RevantCI]

Reviewed all files except crud.py and router.py.
Will review them after the UI is integrated feature by feature.
Merging the PR for now .
Other setup and config files look good.