[Search] Send to background UI

**Describe the feature:**

Reusable connected component to:
* send current search to background
* display async search state 

![image](https://user-images.githubusercontent.com/3756330/98014049-23baaa80-1dc9-11eb-8c55-d049a05d9265.png)



Mocks: https://whimsical.com/LMKSnR7vmPrmAypPXYuA8T
Part of https://github.com/elastic/kibana/issues/61738
