Facets and aggregation support

The UI for displaying the facets that comes from Elasticsearch should look like the attached mock-up.
Behaviour is the following:

• First, the content view search filter is displayed on the left.
• User start filling some fields of the filter and click on search
• Result is displayed and the search filter on the left is replaced by the set of aggregates value selectors. On top of the search result, already selected values among aggregates of that content view are each of them displayed as a small box with as small icon for "unselecting" them.
• User can select new values among the aggregate selectors, result is updated accordingly and in an ajax mode. (no need to click on "submit")

There are several type of aggregates value selectors:

• Vocabularies: display the label of the values of the directory that are in the search result, for a given xpath
• User: display the user first names and last names of the users that are part of the search result, for a given xpath
• Document: Display the document title (configurable xpath is even better) of all the documents that are referenced in the search result, for a given xpath.
• Date. For dates, we display projections by days or month, (and need to check if it coud also be : last day, last week, last month), for a given xpath
  In the future we will also add counts, average, and geobounds, geo distance etc, not in the scope of the first implementation.

A Reset button allows to go back to the empty search, where the initial search filter is displayed.

Aggregates support on a content view is configured from Studio. In an "aggregates" section of the result tab, user enables the aggregates feature. User then configures an aggregates value selector layout, specifying which field of the document is targeted (xpath) and which type of aggregates value selector is to be used.

For now, only the DAM content view template will leverage this capability.