Add task tags for multimodal datasets
## **Is your feature request related to a problem? Please describe.**

Currently, task tags are either exclusively related to text or speech processing:
- https://github.com/huggingface/datasets/blob/master/src/datasets/utils/resources/tasks.json

## **Describe the solution you'd like**

We should also add tasks related to:
- multimodality
- image
- video

CC: @VictorSanh @lewtun @lhoestq @merveenoyan @SBrandeis 
The Hub pulls these tags from [here](https://github.com/huggingface/hub-docs/blob/main/js/src/lib/interfaces/Types.ts) (allows multimodal tasks) now, so I'm closing this issue.