Current Store API prevents us from properly upgrading to the upcoming ibc v0.20.0

[plafer]

The current Store API only allows us to set serialized values.

This is incompatible with the upcoming ibc v0.20.0 which implemented ADR 4. Specifically, we would like to store Box<dyn ClientState> for the client_state_store, and Box<dyn ConsensusState> for the consensus_state_store. We can't store the serialized version, because we don't know how to transform Vec<u8> -> Box<dyn ClientState> without additional information (e.g. the ClientId).

One solution is to create an enum of all types stored in the IBC store (Sequence, PacketCommitment, Box<dyn ClientState>, etc), and have that enum be the type of the value for the IBC store. Proofs will work just fine as well; we just need to ensure that the values in the store are properly serialized before they're fed to the proof algorithm, which I believe is already the case (here and here for example).