Support katstore64 API
Support katstore64 API

Since CAM v24 release the katstore API has changed to katstore64.
This does away with the need to query the sensor KATCP type, since the
HTTP request now returns a JSON string with the appropriate value type.
Having one HTTP request instead of two speeds things up, on top of the
improved performance of katstore64 itself.

This addresses JIRA ticket SR-1962.

ska-sa/katdal