[ENHANCEMENT] Change ReadCollection DTO to default date when all data is to be returned

[neilfromcork]

Any ReadCollection request with either a null date or a date from before the first release will have the same result. This fix is to change the DTO constructor to give the same parameters and hence the same cache key for all such requests.
Earliest date can be read from the database and cached.

[neilfromcork]

Temporary fix in 8.4.0. The 9.0.0 version will read the earliest release date from the database and cache the result.