Mirrors the C++ enum ProxyReEncryptionMode in
pke/constants-defs.h. The R-side name PREMode is a shortened
form, the same pattern as Feature for PKESchemeFeature.
Value
A named list of 4 integer scalars, each the value of the
OpenFHE C++ enumerator of the same name, naming the security notion
the re-encryption key should satisfy: INDCPA,
FIXED_NOISE_HRA or NOISE_FLOODING_HRA, the last two being
honest-re-encryption-attack secure. NOT_SET disables proxy
re-encryption. Pass an element as the pre_mode argument of
CKKSParams(), BFVParams(), BGVParams() or fhe_context().