Add a 'cancel task' option

[tacman]

I've started to use semantic search, one of my favorite new features of meilisearch. I inadvertently triggered a re-vectorization of a dataset (I dropped a field) which meant that it sent my entire dataset to OpenAI again. I wanted to cancel the task (it's both slow and has a cost associated with it), and was hoping there would be a "cancel task" option either next to "Details" or in the popup.

It took about 5 minutes to complete the task.