Rewrite /user/current to Go

[ocket8888]

I'm submitting an ...

improvement request (usability, performance, tech debt, etc.)

Traffic Control components affected ...

• Documentation (possibly)
• Traffic Ops

Current behavior:

/user/current is handled by Perl

Expected / new behavior:

/user/current should be handled by Go.

Minimum API Version

1.1

Request Methods

• GET (Add Traffic Ops Golang user/current #2405)
• PUT

Minimal reproduction of the problem with instructions:

N/A