[zk-sdk] Expose ElGamal and authenticated encryption ciphertext types for wasm target

[samkim-crypto]

Problem

The ElGamal and authenticated encryption types are not yet exported for wasm target build.

Summary of Changes

I exported the ElGamal and authenticated encryption types for wasm target in a sequence of steps.

fb298c9: I first added the zeroed() function for the PodElGamalPubkey. Default values for types are useful when initializing types like mint or account in typescript. I first tried exporting default(), but there did not seem to be a clean way to do it without manually implementing the Default trait.

b6f4fff: The JS logic for PodElGamalCiphertext and PodAeCiphertext are very similar to that of PodElGamalPubkey, so I made a macro for the JS logic.

36adba2: I exported the ElGamalCiphertext related types for wasm. I am just exporting the types for now. I will deter exporting encryption or decryption in subsequent PRs as they are not needed to generate the instruction data for the majority of confidential transfer instructions.

0ebd97e: I exported the AeCiphertext and AeKey related types and functions for wasm. Here, I did include the encryption function since we will need the encryption of 0 to properly configure account data.

bda4976: In TS, camelCase is standard while in rust snake_case is standard. Previously, I just exported out the new_rand() function as is, but I figured out a way to specify js_name, so I updated the names to newRand().

Fixes #