ICS02 mock extensions + more tests in ICS02 and ICS03

[adizere]

Closes: cosmos/ibc-rs#114

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For contributor use:

• Unit tests written
• Added test to CI if applicable
• Updated CHANGELOG_PENDING.md
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Updated relevant documentation (docs/) and code comments
• Re-reviewed Files changed in the Github PR explorer

[codecov-commenter]

Codecov Report

Merging #222 into master will increase coverage by 25.6%.
The diff coverage is 56.8%.

@@            Coverage Diff            @@
##           master    informalsystems/hermes#222      +/-   ##
=========================================
+ Coverage    13.6%   39.2%   +25.6%     
=========================================
  Files          69      78       +9     
  Lines        3752    5257    +1505     
  Branches     1374    1794     +420     
=========================================
+ Hits          513    2065    +1552     
- Misses       2618    3044     +426     
+ Partials      621     148     -473     

Impacted Files	Coverage Δ
modules/src/events.rs	0.0% <ø> (ø)
modules/src/ics02_client/events.rs	0.0% <ø> (ø)
modules/src/ics02_client/raw.rs	0.0% <0.0%> (ø)
modules/src/ics03_connection/error.rs	11.5% <0.0%> (-21.8%)	⬇️
modules/src/ics04_channel/error.rs	23.0% <0.0%> (-2.0%)	⬇️
modules/src/ics04_channel/packet.rs	0.0% <0.0%> (ø)
modules/src/ics07_tendermint/client_def.rs	0.0% <0.0%> (ø)
modules/src/ics07_tendermint/error.rs	33.3% <0.0%> (+33.3%)	⬆️
modules/src/ics07_tendermint/msgs/update_client.rs	0.0% <0.0%> (ø)
modules/src/mock_client/client_def.rs	0.0% <0.0%> (ø)
... and 124 more

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[romac]

LGTM! 👍

[ancazamfir]

I think this should be in the client context. We can discuss and change it in a different PR.

[ancazamfir]

Looks good, one minor comment.