Improving the UI when the program is in "MENTEE_APPLICATION" period

[anjisvj]

There are some improvements that need to be done in the UI when the program is in MENTEE_APPLICATION. I already created issues for the relevant tasks.

Show only the approved mentors in apply as a mentee view

Improve the mentor view in apply as a mentee view

Prevent user from applying as both mentee and mentor for the same program