Problem

• We need an Object FheEncryptionKey
• each FheEncryptionKey object is unique across the JS V8 runtime
• Multiple FhevmRuntime instances sharing the same relayerUrl get the same FheEncryptionKey object
• The 50MB cost is paid once per relayerUrl, regardless of how many runtimes or clients exist.
• each FheEncryptionKey object is immutable from the outside of the SDK
• embeds a publicKey data either in Bytes form or in Wasm form
• can be serialized from wasm form to a JS compatible format
• can be deserialized from its JS compatible format to bytes form
• if the WASM module is available in the runtime : deserialize in wasm form directly
• the FheEncryptionKey object is the only public-facing object
• Behind the scene, there is a cache global
• the cache key is relayerUrl
• FheEncryptionKey is unique per relayerUrl
• the FheEncryptionKey can secretly mutate into its wasm form at any moment
• The goal of the bytes to wasm xform is to ensure the SDK does not keep 2x50MB bytes of data
• The problem of the current cache approach is that it is not complete: there is no "magical" object that auto-mutates from bytes to wasm. Maybe the user-facing object should be a Wrapper to the cache entry ?