Quick wins regarding optimization on various aspects including performance with the field types/domains reading (#3347)

* Simplified the code when doing updateFilters with regards to formatting the date string

* Cleanup

* Moved common delete function from feature-info-event-processor and data-table-event-processor into a helper function

* Deleted the configs/validator folder (legacy configs)
Fixed the demo-important-layers.html template page (was broken and wouldn't add layers when clicking the 'add' button)
Removed legacy layerFilter properties on source objects for EsriDynamic and EsriFeature types

* Few fixes on the opacity adjustments when using the highlight function:
 - Not doing the zIndex thing anymore
 - Not changing to '100%' opacity the layer we want to highlight anymore, leaving it untouched
 - Better management of the opacity through groups)

* Rebvased and removed the getFieldType and getFieldDomain overrides for EsriImage that were recently added

* Integrated peer comments
Can delete a layer that's not existing (only existing through the config)

Author: Alex-NRCan