Fix upgrade-client issues and refactor relevant tests

[Farhad-Shabani]

Closes: #385
Closes: #671
Closes: #672

Description

Check out Basecoin-rs PR99 for the new integration test covering client upgrades.

Note:

• With the current implementation, all comet-based chains can upgrade their clients on hosts using IBC-rs, but hosts for handling an upgrade proposal must figure out the implementation suits their architecture, but can use the newly defined APIs here for setting/getting upgraded_client/cons_state.

• The new APIs haven't been implemented for MockContext yet because both it and its storage will be undergoing changes. Additionally, the methods aren't callable anywhere for testing purposes due to the lack of an upgrade proposal handler.

---

PR author checklist:

• Added changelog entry, using unclog.
• Added tests.
• Linked to GitHub issue.
• Updated code comments and documentation (e.g., docs/).
• Tagged one reviewer who will be the one responsible for shepherding this PR.

Reviewer checklist:

• Reviewed Files changed in the GitHub PR explorer.
• Manually tested (in case integration/unit/mock tests are absent).

[codecov]

Codecov Report

Patch coverage: 87.67% and project coverage change: +0.12 🎉

Comparison is base (ccd6a97) 72.86% compared to head (736a7d2) 72.99%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #673      +/-   ##
==========================================
+ Coverage   72.86%   72.99%   +0.12%     
==========================================
  Files         113      113              
  Lines       15258    15304      +46     
==========================================
+ Hits        11118    11171      +53     
+ Misses       4140     4133       -7     

Impacted Files	Coverage Δ
...bc/src/clients/ics07_tendermint/consensus_state.rs	85.71% <ø> (+5.50%)	⬆️
crates/ibc/src/core/handler.rs	88.60% <ø> (ø)
crates/ibc/src/core/ics02_client/error.rs	20.83% <ø> (ø)
crates/ibc/src/hosts/tendermint.rs	0.00% <0.00%> (ø)
...s/ibc/src/core/ics02_client/msgs/upgrade_client.rs	80.26% <73.33%> (-4.28%)	⬇️
...s/ibc/src/clients/ics07_tendermint/client_state.rs	69.34% <82.97%> (+1.36%)	⬆️
...bc/src/core/ics02_client/handler/upgrade_client.rs	90.64% <93.68%> (+0.98%)	⬆️
crates/ibc/src/core/ics23_commitment/commitment.rs	73.56% <100.00%> (+0.94%)	⬆️
crates/ibc/src/core/ics24_host/path.rs	81.19% <100.00%> (+0.04%)	⬆️
crates/ibc/src/mock/context.rs	73.98% <100.00%> (+0.02%)	⬆️

... and 5 files with indirect coverage changes

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[plafer]

👌