[Discover] Deangularize result counter

[kertal]

The part of Discover displaying the result count of a query, and providing a link to reset a query if a saved search is loaded is still Angular. This should be converted to React + EUI.

It's the following part of Discover's template:

kibana/src/plugins/discover/public/application/angular/discover.html

Line 92 in 33b3c7b

<div class="dscResultCount">

The component should be located in: /src/plugins/discover/public/application/components

The new component needs to registered as a react directive like this:

export function createNewReactComponentDirective(reactDirective: any) {
  return reactDirective(
    NewReactComponent,
    [
      ['nicePropA', watchDepth: 'value' }],
    ],
  );
}

This function needs to be registered in Discover's inner Angular like here

https://github.com/elastic/kibana/blob/master/src/plugins/discover/public/get_inner_angular.ts#L210

And can be used like this

<new-react-directive
     nice-prop-a="variableAssignedInScope"
></new-react-directive>

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)