[FEATURE] Signal slot, search facets, grid parameters

* Add a signal slot for post processing the matcher object
* Set default settings to the query settings relevant in the BE
* Add facets configuration key
* Centralise some labels
* Add processing of parameters to be passed to the grid

Change-Id: I34ebacdd8845c637cda55481190fa3ca62f56571
Releases: 0.2.0
Fixes: #52210