FindCommerce should allow temporarily disabled event indexing

Description

Fixed issue with ability to set FindCommerce event indexing to allow for temporarily disabling of event indexing. 

CatalogContentClientConventions.AllowIndexingCatalogContent should be possible to set dynamically. Furthermore, IsListeningToPriceEvents, IsListeningToInventoryEvents and IsListeningToLowLevelApiEvents should be introduced, and also possible to set dynamically to allow fine grain control of the indexing.