Extend Optional Parameters for Context

[christopherngutierrez]

Proposed changes

• Adds optional parameters for CONTEXT after rns parameters. Optional parameters are defined as key/value pairs (e.g. krns_delta=1).
• Adds optional parameters for krns_delta and num_digits. krns_delta keyword is now required (krns = rns + krns_delta) and num_digits will be use in a future feature.
• Added test cases for invalid optional parameter formatting.

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