Index records instead of entities

[paulandrieux]

At this time we ask elastic to index widget contents, views and all the business entities.
When we start a search, there is 3 subrequests (Widget, View, BusinessEntity).

This is problematic for two reasons:

1. the BusinessEntity results leads to the compilation of all the relative BusinessPages, the number of generated views is unpredictable, so we cannot limit the results neither use a pager.
2. The boosts defined at indexation are not reliable because of this 3 requests.

A solution would be to change our paradigm and do not index entities anymore but index records reflecting all the sitemap.
A record element should be defined with all the indexable fields of both widgets, views and businessEntities (through the serializer group "search"). When a query is ran, there will be only one index to check and the found records could be used to generate the search result links.