Implement missing IBC APIs for Skip

[zbuc]

From Skip:

I took a look at which grpc endpoints are working that Skip API depends on, and most of the IBC ones seem to work. I found three that we depend on that would be benefitial if we could have them implemented.

cosmos.bank.v1beta1.Query/TotalSupply
https://github.com/cosmos/cosmos-sdk/blob/main/x/bank/proto/cosmos/bank/v1beta1/query.proto#L57

ibc.applications.transfer.v1.Query/DenomTraces
https://github.com/cosmos/ibc-go/blob/main/proto/ibc/applications/transfer/v1/query.proto#L16

ibc.core.client.v1.Query/ClientStatus
https://github.com/cosmos/ibc-go/blob/main/proto/ibc/core/client/v1/query.proto#L47

[zbuc]

@hdevalence Implementing the IBC APIs seems straightforward but cosmos.bank.v1beta1.Query/TotalSupply seems a little trickier as it's part of a larger CosmosSDK-specific RPC interface. Do we think it would be suitable to build a similar query within the existing shielded_pool API, or do we need to implement this specific call?

[aubrika]

@hdevalence Implementing the IBC APIs seems straightforward but cosmos.bank.v1beta1.Query/TotalSupply seems a little trickier as it's part of a larger CosmosSDK-specific RPC interface. Do we think it would be suitable to build a similar query within the existing shielded_pool API, or do we need to implement this specific call?

We should implement this specific call, but we may not include everything expected on other chains - this is for compatibility and may be idiosyncratic.

[conorsch]

WIP PR here: #4404

[hdevalence]

This needs to implement the specified RPC: #4404 (comment)

Now that we merged a new RPC that we don't want we have to either deprecate it or do a breaking proto change.

[hdevalence]

We need to immediately delete the following messages newly added to the Penumbra protobufs, before they are picked up and used:

rpc TotalSupply
TotalSupplyResponse
TotalSupplyRequest

The point of the issue was to implement the expected RPC, not to make up our own incompatible one.

[conorsch]

We have a follow-up PR intended to close this out: #4444

[conorsch]

Resolved via #4444