Avoid unwrap() for Height conversion

[adizere]

Closes: #300

This fixes most of the try_into().unwrap() around Height type conversion. The unwraps were recently necessary for a quick alignment with tendermint-rs changes in Height type.

Several uses of try_into().unwrap() still exist in our code in places where it was difficult to fix (some in relayer-cli) or places which are currently in flux (context mocks, which will be removed soon).

Description

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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-io]

Codecov Report

Merging #301 into master will increase coverage by 23.3%.
The diff coverage is 61.8%.

@@            Coverage Diff            @@
##           master    #301      +/-   ##
=========================================
+ Coverage    13.6%   37.0%   +23.3%     
=========================================
  Files          69     120      +51     
  Lines        3752    7788    +4036     
  Branches     1374    2785    +1411     
=========================================
+ Hits          513    2885    +2372     
- Misses       2618    4586    +1968     
+ Partials      621     317     -304     

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/raw.rs	0.0% <0.0%> (ø)
modules/src/ics03_connection/context.rs	0.0% <0.0%> (ø)
modules/src/ics03_connection/error.rs	16.6% <0.0%> (-16.7%)	⬇️
modules/src/ics04_channel/error.rs	75.0% <ø> (+50.0%)	⬆️
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	75.0% <ø> (+75.0%)	⬆️
modules/src/ics18_relayer/error.rs	0.0% <0.0%> (ø)
... and 218 more

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[romac]

Thanks @adizere!