Implement historical endpoint

[sfirke]

Note from the description of the startTime parameter when querying Recent Measurements:

Cut-off time for the earliest measurement desired. If not specified, the start time used will be chosen based on the requested output frequency
minute → 1 hour prior to time of request
hour → 24 hours prior to time of request
day → 48 hours prior to time of request

Measurements are returned from a cache. Earlier times are accepted in the parameter, but only data from the cache will be returned.

Say you want the last week of hourly measurements. The hourly cache only goes back 48 hours so there is no way to query that from the recent measurements endpoint.

It would be nice if this could be implemented such that the user can use the same clarityio call and simply specify "historical" as the endpoint, but I haven't yet looked to see if the interfaces are similar enough for that to be reasonable.