add the autocomplete filter

[link2qaiser]

#192 Username autocomplete endpoint
Add the DRF filter for Search critaria

[MAbdurrehman1]

I don't think we should make a separate file/view for this. I think, we can reuse the existing viewset, and introduce some generic searching to it.

ps: Instead of specific user search with username only, can we have a generic search?
Where I can have a list of search_fields and the searching can be done according to those.

EXACTLY how Django does it in the admin side:

and all the searching is being controlled by just this search_fields configuration:

Note: I think we are already using django_filters so it can be re-used here.