Feature: Update Mentor matching

[apex-omontgomery]

Description

Improve mentor alerts in the mentor channel to give more context.

1. If less than 3 values found for the mentor matched use the partial matching.
2. Display requested mentor
3. The username is determined by email, when a email-> username value is not found this provides an unclear value, make this better.

Purpose

Provide a better experience for mentors.

[AllenAnthes]

1 and 2 are currently in staging. Regarding 3 should we just display the email along with a message stating that a slack account couldn't be found?

[apex-omontgomery]

That sounds like a good compromise.

[AllenAnthes]

Completed.