Improve existing entity search functionality

From Eddie on PRODUCT-2:

"Search" entities in connector or adapter - it would be great to have an option to enter search criteria first rather than have to list all then sort.
It is probably not so bad in many sites, but DET as an example, takes an age to load 109,000 entities, which is a pain when we only want to look at one.

This issue is subject to whatever searches the current database structure can provide. For example, "Starts with" should be fine - "Contains" probably not. Date ranges may or may not be possible. Further investigation and comment required.