refactor: hd team and hd agent

[RitvikSardana]

Issue
Currently we have duplicated data.

1. HD Team: This DocType has a table of Users.
2. HD Agent: This DocType has a table of HD Team.

Solution:
The correct way is to have control on Team level, that is remove the table from HD Agent, and only support from HD Team.

What Changed?

1. Wrote a patch for the same
2. Removes Groups Table from HD Agent DocType and removed related functions.
3. Updating HD Team will update users in the Assignment Rule. (On changing HD Team Users => Update the assignment rule (previously done by HD Agent))
4. Refactor HD Ticket => Write functions which uses HD Team users instead of HD Agent Groups.