Bugfix - Enumerating collection with documents expiring causes early return

[jrpavoncello]

Addresses bug found in #421 i.e. enumerating a collection from a search where the documents were expiring causes an early return resulting in less documents than expected.

@slorello89 Side note - I noticed that the non-generic SearchResponse would return an empty Document i.e. an empty dictionary documentHash, akin to returning null. But the generic SearchResponse<T> just skips the document instead. In the same vein, AggregationResult and AggregationResult<T> also seem to have a general pattern of returning null to their callers (whether internal or external to this package). This seemed like an unexpected functional difference between these classes that all handle a RedisReplys so I wanted to call it to your attention for potential future review since these would be out of scope of a patch.

[jrpavoncello]

@slorello89 Hey Steve, I wasn't sure if you got notifications from PR descriptions so here's an extra ping if not :) I wanted to get your thoughts on the "side note" mentioned there before publishing this PR, I found some stuff that is probably out of scope for this change.

[slorello89]

Hi @jrpavoncello - AggregationResults are a bit different in that they will actually return null items based on what's in the pipeline:

127.0.0.1:6379> FT.AGGREGATE catalogentry-idx * LIMIT 0 10
 1) (integer) 1
 2) (empty array)
 3) (empty array)
 4) (empty array)
 5) (empty array)
 6) (empty array)
 7) (empty array)
 8) (empty array)
 9) (empty array)
10) (empty array)
11) (empty array)

WRT to the non-generic version of SearchResponse, I think that I left that there in case someone wanted a more raw version of the Search Response someday, which wasn't a need that ever materialized, so realistically it's probably dead code which should be removed at some point.

[slorello89]

LGTM 👍 thanks for submitting this @jrpavoncello