WIP Investigation into replacing anomaly with eyre for error handling

[adizere]

Closes: #68

The PR in its current form is an experiment with replacing anomaly with eyre.
Only the following components have transitioned to eyre:

• ICS02 (completely)
• relayer-cli (the part about keys commands)
• relayer (only some modules related to key manipulation)

If we're satisfied with eyre, we'll continue porting all of ibc-rs in a couple more separate PRs.

Discussion here: #68 (comment)

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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 #493 (f165f26) into master (b1b37f5) will increase coverage by 15.6%.
The diff coverage is 54.3%.

@@            Coverage Diff            @@
##           master    #493      +/-   ##
=========================================
+ Coverage    13.6%   29.3%   +15.6%     
=========================================
  Files          69     160      +91     
  Lines        3752   12891    +9139     
  Branches     1374    4989    +3615     
=========================================
+ Hits          513    3785    +3272     
- Misses       2618    8418    +5800     
- Partials      621     688      +67     

Impacted Files	Coverage Δ
...application/ics20_fungible_token_transfer/error.rs	0.0% <ø> (ø)
...pplication/ics20_fungible_token_transfer/events.rs	0.0% <ø> (ø)
...ion/ics20_fungible_token_transfer/msgs/transfer.rs	0.0% <0.0%> (ø)
modules/src/events.rs	0.0% <0.0%> (ø)
modules/src/ics02_client/events.rs	0.0% <0.0%> (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	6.8% <0.0%> (-26.6%)	⬇️
modules/src/ics03_connection/events.rs	0.0% <0.0%> (ø)
modules/src/ics04_channel/error.rs	13.0% <0.0%> (-12.0%)	⬇️
... and 287 more

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[adizere]

Retiring this PR, we'll leave the work for later.