Sanitize mentee public endpoint and sanitize mentor details

[Madhawa97]

Purpose

The purpose of this PR is to fix #149

Goals

Hide unwanted fields from the returned data

Approach

• Create a public get mentee endpoint

• Protect existing endpoints

• Implement proper util methods

• Also adds fix for getMenteesSchema

Screenshots

Checklist

• [x] This PR doesn't commit any keys, passwords, tokens, usernames, or other secrets.
• [x] I have read and understood the development best practices guidelines ( http://bit.ly/sef-best-practices )
• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation

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