Replace /extension-requests/self with /extension-requests/user/:userId for fetching extension requests

[RishiChaubey31]

Issue Description

• Currently, we use the endpoint /extension-requests/self to retrieve all extension requests for the logged-in user. However, we should transition to using the endpoint /extension-requests/user/:userId to align with the updated API structure and improve clarity and consistency.

expected Behaviour

• The system should fetch extension requests using /extension-requests/user/:userId, where :userId is dynamically replaced with the logged-in user's ID. This provides a more RESTful and scalable API design.

current behaviour

• The system currently fetches extension requests using the endpoint /extension-requests/self, which is hardcoded to get data for the authenticated user.

Reference

• https://github.com/Real-Dev-Squad/website-api-contracts/pull/206/files