imp: make custom `Validation/ExecutionContext` under ICS-07 usable by any light clients

[Farhad-Shabani]

Closes: #1163

Step before: #1167

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PR author checklist:

• [X] Added changelog entry, using unclog.
• [X] Linked to GitHub issue.
• [X] Updated code comments and documentation (e.g., docs/).
• [X] 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[bot]]

Codecov Report

Attention: Patch coverage is 78.78788% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 63.79%. Comparing base (c659e21) to head (278c609).

Files	Patch %	Lines
...nts/ics07-tendermint/src/client_state/execution.rs	68.75%	5 Missing :warning:
...ts/ics07-tendermint/src/client_state/validation.rs	75.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1166 +/- ## ======================================= Coverage 63.79% 63.79% ======================================= Files 219 219 Lines 21391 21389 -2 ======================================= - Hits 13647 13646 -1 + Misses 7744 7743 -1 ```

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