CKKS Bug Fixes for Relin/Rotate/Mod/Rescale (RNS > 3)

[christopherngutierrez]

Proposed changes

• Fixed bug in mod that produced unused instructions
• Fixed bug in rescale that produced unused instructions
• Added new option in Polys.from_polys to set RNS=1. Used in bug fixes.

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
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[kylanerace]

Ran and LGTM. Will need to do a wider test a bit later.