jf_activity: paginated list in ui

added POST route for pagination to activity route, a count route, and
modified Search and PaginatedList a bit to support lists without search
fields (essentially just running an empty search). Visible by clicking
on a user's name in the accounts tab.

usercache.go

@@ -599,18 +599,6 @@ func (q *QueryDTO) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// ServerSearchReqDTO is a usual PaginatedReqDTO with added fields for searching and filtering.
-type ServerSearchReqDTO struct {
-	PaginatedReqDTO
-	ServerFilterReqDTO
-}
-
-// ServerFilterReqDTO provides search terms and queries to a search or count route.
-type ServerFilterReqDTO struct {
-	SearchTerms []string   `json:"searchTerms"`
-	Queries     []QueryDTO `json:"queries"`
-}
-
 // Filter reduces the passed slice of *respUsers
 // by searching for each term of terms[] with respUser.MatchesSearch,
 // and by evaluating Queries with Query.AsFilter().