apps.paint annotations Add option to filter iscrowd

apps.paint annotations Add option to filter iscrowd: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). ! 000000545959 result (https://user-images.githubusercontent.com/12677733/107704160-1b71e580-6cbd-11eb-9e56-e964b6e2aec9.jpg)