Feat/integrate database layer

[Dev-GA-Arjun]

Completed Module 3 Project Integration

Changes Made in this Module:

1. Created MongoDB Cluster and connected with the Blogify-API with mongoose ODM
2. Created Collection such as Posts and User and use Referencing to connect User and Posts with One-to-Many Relationship.
3. Created Service Layer and Refactored Controllers to handle only req and res unlike before.