Create a core config package which will have all the constants

[MehulKChaudhari]

Issue Description

Create a core config package move all const to this config package, then consume the configs

instead of this https://github.com/Real-Dev-Squad/feature-flag-backend/blob/d640dca1d9d2c4d53225382b0ac5f24e98ac0363/jwt/jwt.go#L40

We have to do something like this.
example:
https://github.com/Real-Dev-Squad/tiny-site-backend/blob/develop/config/core-config.go
https://github.com/Real-Dev-Squad/wisee-backend/blob/develop/src/config/core-config.go