feat(ibc-testkit): revamp `MockContext` with chain capabilities

[rnbguy]

Closes: #1045

Description

• takes account of new ClientStateValidation and ClientContextValidation
• introduces block production using Merkle root
• begin_block and end_block methods for MockContext
• removes clippy lints in ibc-testkit

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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[bot]]

Codecov Report

Attention: Patch coverage is 89.28571% with 69 lines in your changes are missing coverage. Please review.

Project coverage is 67.76%. Comparing base (cb6ca8b) to head (72c2a0e).

Files	Patch %	Lines
ibc-testkit/src/context.rs	92.93%	25 Missing :warning:
ibc-testkit/src/testapp/ibc/core/core_ctx.rs	57.14%	21 Missing :warning:
ibc-testkit/src/hosts/mock.rs	71.42%	6 Missing :warning:
ibc-testkit/src/hosts/tendermint.rs	86.04%	6 Missing :warning:
ibc-testkit/src/hosts/mod.rs	91.11%	4 Missing :warning:
ibc-testkit/src/testapp/ibc/core/types.rs	89.74%	4 Missing :warning:
ibc-testkit/src/fixtures/core/context.rs	94.44%	2 Missing :warning:
ibc-testkit/src/testapp/ibc/clients/mod.rs	91.66%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## feat/refactor-testkit #1135 +/- ## ========================================================= + Coverage 66.71% 67.76% +1.04% ========================================================= Files 213 213 Lines 20800 20108 -692 ========================================================= - Hits 13877 13626 -251 + Misses 6923 6482 -441 ```

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[rnbguy]

I managed to write a minimal proof verification test with Tendermint light client. For now, it uses the ProofSpecs of basecoin_store.

To keep the proof retrieval minimal, I had to modify the ProvableContext::get_proof of MockIbcStore. Before it returned the encoded bytes of a singleCommitmentProof. Now it returns the encoded bytes of MerkleProofs, which is essentially a list of CommitmentProofs corresponding to a MerklePath.

Two shortcomings of basecoin_store:

• No support for cosmos-sdk specs informalsystems/basecoin-rs#171
• No support for non-membership proofs informalsystems/basecoin-rs#158

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Ignore this comment - as the changes related to this will be processed in a separated PR.

[rnbguy]

That was a good suggestion. While doing that, I realized that the chain ID (and revision number) are not that relevant for our test cases. We can actually totally remove the chain_ids and use fixed zero as a default revision number. It is only needed to test client upgrades.

I still kept it as some of the tests are using Height::new(1, <height>). Let's refactor the following in future PR:

• Add TestHost::revision_number that is only necessary for producing blocks (for a host with no concept of chain ID - this would just return zero)
• Make latest_height in MockContextConfig to be just revision height i.e. u64 (as the Context does not need to deal with revision_number - this should be dealt via TestHost implementation)