Add redirection from /my-discussions to the my discussion page

Problem/Motivation

Add a redirect from /my-discussions path to /user/{user-id}/discussions of current user. It will smoth the user-experience.

Steps to reproduce

N/A

Proposed resolution

Create a route that redirects the user if he is logged in.

Remaining tasks

N/A

User interface changes

N/A

API changes

N/A

Data model changes

N/A