Ibc query support

[ethanfrey]

Closes #434

Code "complete", but needs testing

The IbcQuery.Channels variant doesn't seem to match what we can get from the IBC Keeper (we cannot filter by port). This will be very expensive to call.

Let us reconsider what we want to do here. We can still modify the queries we expose to the contracts (remove or adjust them). CosmWasm is still in -alpha2, so we can change types.

[codecov]

Codecov Report

Merging #439 (9ce450a) into master (d51a1b8) will decrease coverage by 0.85%.
The diff coverage is 26.98%.

@@            Coverage Diff             @@
##           master     #439      +/-   ##
==========================================
- Coverage   55.44%   54.58%   -0.86%     
==========================================
  Files          39       39              
  Lines        4080     4109      +29     
==========================================
- Hits         2262     2243      -19     
- Misses       1627     1671      +44     
- Partials      191      195       +4     

Impacted Files	Coverage Δ
x/wasm/internal/keeper/query_plugins.go	59.74% <9.80%> (-13.77%)	⬇️
x/wasm/internal/keeper/keeper.go	87.06% <100.00%> (-0.87%)	⬇️
x/wasm/internal/keeper/relay.go	100.00% <100.00%> (ø)

[alpe]

Minor comments only. Looks good 🌻

[ethanfrey]

I'd like to make a few changes to the query types as mentioned above. Do you think those are good?

• Remove the port argument to Channels query (as we basically ignore it, filtering could be done just as easy in wasm). (Keep it there and fake sdk side, future versions may provide better queries)
• Include full channel info in the list query (we have it all)
• Remove the Counterparty Version info from the ChannelInfo

[alpe]

I'd like to make a few changes to the query types as mentioned above. Do you think those are good?

• Remove the port argument to Channels query (as we basically ignore it, filtering could be done just as easy in wasm). (Keep it there and fake sdk side, future versions may provide better queries)
  👌

• Include full channel info in the list query (we have it all)
  👌 Can save further queries

• Remove the Counterparty Version info from the ChannelInfo
  🙅 We need it during IBC handshake. Maybe we make it a pointer type to communicate that it is not always set.