Interactive 2party bootstrapping

[yspolyakov]

See Appendix D of https://eprint.iacr.org/2023/1203 for details.

• Initially enabled it only for CKKS. However, later this implementation can be extended to BGV and BFV. So the functions were added with this in mind.
• Added IntBootDecrypt, IntBootAdd, and IntBootEncrypt to the parent RNS scheme (MultipartyRNS).
• Added IntBootAdjustScale (special scaling for CKKS) to MultipartyCKKSRNS.
• Initially only one extra tower will be used for bootstrapping. Later we will make it a configurable parameter. To add the tower, the multiplicative depth needs to be increased by 1.

[yspolyakov]

Notes for @dsuponitskiy

1. Convert unit-test-interactive-bootstrapping.cpp to unit tests. Include FIXEDMANUAL, FIXEDAUTO, and FIXEDAUTO. Use 1024 as the ring dimension. Support both HYBRID and BV key switching methods. Delete the example after the unit tests are added.
2. Add unit tests for all scenarios of interactive-bootstrapping.cpp (set ring dimension to 1024). Support both HYBRID and BV key switching methods.
3. Review the code with the main logic.

Once these are completed, I will revise interactive-bootstrapping.cpp to add more comments and reduce the number of options.

[yspolyakov]

I still need to clean up interactive-bootstrapping.cpp