Remove Cassini ISS offset

[rfrenchseti]

There is a NAC/WAC offset hard-coded in the Cassini ISS hosts module that I derived from previous navigation work, but I do not have confidence in this number or (based on information from Joe) the possibility that it might vary over time. Thus I'm turning it off by default until we can do further analysis. I think having the offset on by default will do more potential damage. I also removed the same copied code from JUNOCAM, even though that code is apparently never called. All tests still pass with current gold backplanes.

Fixes #96

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.10%. Comparing base (435bae3) to head (088489c).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #124   +/-   ##
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  Coverage   77.10%   77.10%           
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  Files         134      134           
  Lines       24821    24821           
  Branches     2834     2834           
=======================================
  Hits        19137    19137           
  Misses       4829     4829           
  Partials      855      855           

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[jnspitale]

This sounds good to me. The Junocam argument was left over from copying and modifying the Cassini module.