Add keyset pagination for users ordered by username / display_name

[andreaskoepf]

for keyset pagination pass lowest or highest values of last result-set:
gt_id & gte_username or
lt_id & lte_username

/api/v1/users/by_username

all parameters are optional:

api_client_id: str
gte_username: str
gt_id: uuid
lte_username: str
lt_id: uuid
auth_method: str
search_text: str
max_count: int

/api/v1/users/by_display_name

all parameters are optional:

api_client_id: str
gte_display_name: str
gt_id: uuid
lte_display_name: str
lt_id: uuid
auth_method: str
search_text: str
max_count: int

[notmd]

Could this simplify to 1 endpoint and add an extra sort_by column and make default to username or display_name? Also, unify all gt_* and lt_* param into gt and lt too. The back end should return 2 extra fields, next and previous, which are the cursors encoded or encrypted by the backend itself. I'm feeling the front currently needs to specify the param and endpoint just to get users which is too much work here. Let's push more work to the backend instead.

[yk]

thank you