Feat: Add "All assignees" in Task team member dropdown (#1763)

* implemented all select option FilterDropdownEntitySearchSelect and enabled it for tasks page filter

* created new filter operand IsNotNull for make a select all qraphql query, added internal state for tracking isAllEntitySelected

* used filterCurrentlyEdited to track if isAllEntitySelected is selected

* fixed filter button icon SelectAll Icon

front/src/pages/tasks/tasks-filters.tsx

@@ -1,5 +1,5 @@
 import { TasksRecoilScopeContext } from '@/activities/states/recoil-scope-contexts/TasksRecoilScopeContext';
-import { IconUser } from '@/ui/icon';
+import { IconUser, IconUserCircle } from '@/ui/icon';
 import { FilterDefinitionByEntity } from '@/ui/view-bar/types/FilterDefinitionByEntity';
 import { FilterDropdownUserSearchSelect } from '@/users/components/FilterDropdownUserSearchSelect';
 import { Activity } from '~/generated/graphql';
@@ -13,5 +13,7 @@ export const tasksFilters: FilterDefinitionByEntity<Activity>[] = [
     entitySelectComponent: (
       <FilterDropdownUserSearchSelect context={TasksRecoilScopeContext} />
     ),
+    selectAllLabel: 'All assignees',
+    SelectAllIcon: IconUserCircle,
   },
 ];