Relayer tests after integration with MockChain

[adizere]

Closes: #381

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For contributor use:

• Updated the Unreleased section of CHANGELOG.md with the issue.
• If applicable: Unit tests written, added test to CI.
• 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-io]

Codecov Report

Merging #438 (5e67f50) into master (b1b37f5) will increase coverage by 25.5%.
The diff coverage is 68.9%.

@@            Coverage Diff            @@
##           master    #438      +/-   ##
=========================================
+ Coverage    13.6%   39.1%   +25.5%     
=========================================
  Files          69     156      +87     
  Lines        3752   11207    +7455     
  Branches     1374    4316    +2942     
=========================================
+ Hits          513    4392    +3879     
- Misses       2618    6188    +3570     
- Partials      621     627       +6     

Impacted Files	Coverage Δ
modules/src/events.rs	0.0% <0.0%> (ø)
modules/src/ics02_client/events.rs	0.0% <ø> (ø)
modules/src/ics02_client/msgs.rs	0.0% <0.0%> (ø)
modules/src/ics02_client/raw.rs	0.0% <0.0%> (ø)
modules/src/ics03_connection/error.rs	13.6% <0.0%> (-19.7%)	⬇️
modules/src/ics04_channel/error.rs	75.0% <ø> (+50.0%)	⬆️
modules/src/ics04_channel/msgs/chan_open_ack.rs	65.4% <ø> (ø)
...odules/src/ics04_channel/msgs/chan_open_confirm.rs	63.3% <ø> (ø)
modules/src/ics04_channel/msgs/chan_open_init.rs	69.5% <ø> (ø)
modules/src/ics04_channel/msgs/chan_open_try.rs	68.2% <ø> (ø)
... and 288 more

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[adizere]

Closing in favor of a cleaner version #440