Support search request cancellation

[arteymix]

When a new search is issued, we have to cancel the pending one to prevent a race condition. Presently, this means aborting the following requests: datasets, datasets number and datasets annotations.

This is supported by Axios, but not vuex-rest-api. It would be nice to be able to dispatch the store and include a signal to effectively cancel the dispatch later on, or have some built-in mechanism for binding the cancel state to the store. More details at https://axios-http.com/docs/cancellation

The native API for browser is AbortController.

[arteymix]

Looks like this is in the planning in vuex-rest-api... from 3 years ago. christianmalek/vuex-rest-api#104