Convert frozen height to None when raw frozen height is zero

[soareschen]

Fixes #1619

Description

This fixes a conversion error in #1619 which converts a raw zero frozen height to Some(height). This causes the client refresh code to always fail and produce errors in the log that looks like:

2021-12-03T15:15:23.859171Z  WARN ibc_relayer::worker::client: failed to refresh client 'ibc-beta-db1b0834 -> ibc-alpha-d6aefd25:07-tendermint-3':
   0: client 07-tendermint-3 on chain id ibc-alpha-d6aefd25 is expired or frozen

Location:
   /home/ubuntu/.cargo/registry/src/git.luolix.top-1ecc6299db9ec823/flex-error-0.4.4/src/tracer_impl/eyre.rs:10

  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ BACKTRACE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
                                ⋮ 5 frames hidden ⋮
   6: flex_error::tracer_impl::eyre::<impl flex_error::tracer::ErrorMessageTracer for eyre::Report>::new_message::h840ab510e0dd20df
      at /home/ubuntu/.cargo/registry/src/git.luolix.top-1ecc6299db9ec823/flex-error-0.4.4/src/tracer_impl/eyre.rs:10
   7: ibc_relayer::foreign_client::ForeignClientError::expired_or_frozen::h7431f07b814e8973
      at /home/ubuntu/.cargo/registry/src/git.luolix.top-1ecc6299db9ec823/flex-error-0.4.4/src/macros.rs:823
   8: ibc_relayer::foreign_client::ForeignClient<DstChain,SrcChain>::refresh::h0c2eb9dc8d22c66b
      at /development/relayer/src/foreign_client.rs:575
   9: ibc_relayer::worker::client::ClientWorker<ChainA,ChainB>::run::h7a6eaa440ab40f79
      at /development/relayer/src/worker/client.rs:70
  10: ibc_relayer::worker::Worker<ChainA,ChainB>::run::hf27efb7db6ebec06
      at /development/relayer/src/worker.rs:122
  11: ibc_relayer::worker::Worker<ChainA,ChainB>::spawn::{{closure}}::hc3e19b432a406c12
      at /development/relayer/src/worker.rs:111
                                ⋮ 14 frames hidden ⋮

The error was not picked up by the CI because it is an error on the client worker, and therefore does not cause tests to crash.

---

PR author checklist:

• Added changelog entry, using unclog.
• Added tests: integration (for Hermes) or unit/mock tests (for modules).
• Linked to GitHub issue.
• Updated code comments and documentation (e.g., docs/).

Reviewer checklist:

• Reviewed Files changed in the GitHub PR explorer.
• Manually tested (in case integration/unit/mock tests are absent).

[hu55a1n1]

Raw frozen height is defined as an Option here ->

/// Block height when the client was frozen due to a misbehaviour
#[prost(message, optional, tag = "6")]
pub frozen_height: ::core::option::Option<super::super::super::core::client::v1::Height>,

I would've expected gaiad to respond with a None instead of RawHeight::zero() to indicate a client that isn't frozen. Seems to me like a bug in ibc-go(?), although I agree we need this fix for now anyway.

[adizere]

It seem like we need to update the E2E python script. I suspect the CI fails because the frozen_height has to be marked Optional[Height] instead of Height:

https://github.com/informalsystems/ibc-rs/blob/c2f6d2e5282581908f5fae99dda27028888de6fd/e2e/e2e/client.py#L63

[adizere]

Thanks Soares!