Add sensor model support for Calibrated VIRTIS_M_IR and VIRTIS_M_VIS images to ISIS (#647)

* Fixes the reading of SCETs into the ISIS3 table in the ingested image for level-3, calibrated VIRTIS-M images

* Added initial updates to the RosettaVirtisCamera model to support VIRTIS-M calibrated images

* Corrected StartTime and SpacecraftClockStartCount in calibrated VIRTIS-M ingested images and initial camera model cleanup

* Fix spacecraft clock start / stop count and start time and stop time in rosetta virtis labels

* Updated label fix for rosvirtis2isis.

* fixed StopTime and SpacecraftClockStopCount in virtis labels

* Cleanup of camera model

* Fix sclk calculation in rosvirtis2isis, update table attached to ingested cube to include the sclk string, update camera model to use updated table.

* Changes to the RosettaVirtisCamera and SpiceRotation to allow spiceinit with mirror kernels

* Clean up debug output

* Update SpiceRotation's minimize-cache-status setting function to not update if it has been previously set to fixed

* Update SpiceRotation to only set the time cache explicitly if one has not already been loaded from the InstrumentPosition table attached to the cube

* Clean up rosetta virtis changes

* Cleanup of merge of virtis changes