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.

router.go

@@ -207,6 +207,8 @@ func (app *appContext) loadRoutes(router *gin.Engine) {
 		api.POST(p+"/users/extend", app.ExtendExpiry)
 		api.DELETE(p+"/users/:id/expiry", app.RemoveExpiry)
 		api.GET(p+"/users/:id/activities/jellyfin", app.GetJFActivitesForUser)
+		api.GET(p+"/users/:id/activities/jellyfin/count", app.CountJFActivitesForUser)
+		api.POST(p+"/users/:id/activities/jellyfin", app.GetPaginatedJFActivitesForUser)
 		api.POST(p+"/users/enable", app.EnableDisableUsers)
 		api.POST(p+"/invites", app.GenerateInvite)
 		api.GET(p+"/invites", app.GetInvites)