I don't like having to specify the keys to omit when I call `render_hash_as_hidden_fields` -- because the thing calling `render_hash_as_hidden_fields` may be third-party (non core BL) code, but changes in BL may add or remove from the list of keys that should be omitted.  

That's why I thought it made sense for the default list of keys to be omitted to be baked into the method, so the caller woudl not have to know it, and if BL core made changes like adding new params that needed to be omitted, the callers would keep on working, and not have to be changed themselves. The information on what keys to be omitted -- at least part of that information -- is something Blacklight knows, but dependencies should not have to -- 

but dependencies calling `render_hash_as_hidden_fields` should be able to add on their own _additional_ keys to omit, that they know about. Was my thinking