Audit all Penumbra-related todo items

[zbuc]

We audited all existing todo items, replacing them with unimplemented when appropriate and adding more context to the outstanding todo items.

We still have some outstanding questions, for example:

• Should we implement a trusting period in the Penumbra Hermes configs?
• The evidence command is unimplemented and expects a CosmosSDK chain; is this command important?
• Do we need to support genesis reset parameters?
• Do we need to implement IBC channel/client state queries in Penumbra?
• Do we need to implement cross-chain queries?

Closes #19

[conorsch]

Should we implement a trusting period in the Penumbra Hermes configs?

We at least need to make a decision about this (see discord discussion in https://discord.com/channels/824484045370818580/930154881040404480/1235729085515436092), and preferably document it somewhere, and I don't see a better place than the code right now. So my vote is yes.

Do we need to support genesis reset parameters?

Sounds related to, but distinct from, #22, but I lack context.

@avahowell it'd be lovely to have your input on @zbuc's questions!

[avahowell]

Should we implement a trusting period in the Penumbra Hermes configs?

This should be derived from the chain's reported unbonding period, as it's security critical. That's what's currently done in the hermes impl (trusting period = 2/3 of the unbonding period), I think we should not add an ability in the config to override this

The evidence command is unimplemented and expects a CosmosSDK chain; is this command important?

Yes, we should have the ability to automatically detect and submit evidence of equivocation in hermes.

Do we need to support genesis reset parameters?

Yes, this is required in order to support preserving channels after an upgrade. @erwanor and I implemented and exercised this functionality in #22 on one of the recent testnet upgrades

Do we need to implement IBC channel/client state queries in Penumbra?

We have at least some of these implemented already IIRC (that's how the pcli q ibc functionality works). Are there specific ones that are missing?

Do we need to implement cross-chain queries?

Inferring from the PR that this refers to ICS-31; I'm not sure what parts of this we need to support.

[zbuc]

@avahowell currently unimplemented IBC state queries:

• query_upgraded_client_state
• query_upgraded_consensus_state
• query_host_consensus_state
• maybe_register_counterparty_payee
• query_incentivized_packet
• query_consumer_chains