Changes to Assign expert candidates

added the optional property items/items/absence_end_at to the response with the 200 status

added the optional property items/items/absence_start_at to the response with the 200 status

the request property city_id became optional

request property city_id list-of-types was widened by adding types null to media type application/json

added the optional property items/items/assignments_block_reason to the response with the 200 status

added the optional property items/items/assignments_blocked_at to the response with the 200 status

added the optional property items/items/recent_active_delta_3m to the response with the 200 status

added the optional property items/items/recent_assignments_3m to the response with the 200 status

added the optional property items/items/recent_dropouts_delta_3m to the response with the 200 status

added the optional property items/items/recent_trend to the response with the 200 status