feat: restructure mock module and separate its codebase into a new crate

[Farhad-Shabani]

Closes: #953
Closes: #952
Closes: #951

Description

The mock implementation has undergone a comprehensive restructuring aimed at achieving complete decoupling of its various components and organizing them under relevant categories. This should facilitate future enhancements, particularly the addition of new implementations for components such as relayers and mock chains.

This restructuring results in four distinct top-level groups as follows:

• hosts: Encompasses code related to chains, with a particular focus on definitions related to the consensus layer of these chains.
• testapp: Codebases relevant to the application end (state transition machine) of a chain. It may contain various modules, including IBC.
• relayer: Houses types and functionalities required for simulating the role of a mock relayer, facilitating IBC talk between our testing chains.
• utils: Contains utility types, functions, and other tools that assist in writing tests.

By the way, this is the first iteration and we might improve it in the future as we refactor our testing kits.

The new crate is named ibc-testkit, and here is an overview of its directory structure:

.
├── hosts
│   ├── block.rs
│   └── mod.rs
├── lib.rs
├── relayer
│   ├── context.rs
│   ├── error.rs
│   └── mod.rs
├── testapp
│   ├── ibc
│   │   ├── applications
│   │   │   ├── mod.rs
│   │   │   └── transfer
│   │   ├── clients
│   │   │   ├── mock
│   │   │   └── mod.rs
│   │   ├── core
│   │   │   ├── client_ctx.rs
│   │   │   ├── core_ctx.rs
│   │   │   ├── mod.rs
│   │   │   ├── router
│   │   │   └── types.rs
│   │   └── mod.rs
│   └── mod.rs
└── utils
    ├── dummies
    │   ├── applications
    │   │   ├── mod.rs
    │   │   └── transfer.rs
    │   ├── clients
    │   │   ├── mock.rs
    │   │   ├── mod.rs
    │   │   └── tendermint.rs
    │   ├── core
    │   │   ├── channel
    │   │   ├── client
    │   │   ├── commitment.rs
    │   │   ├── connection
    │   │   ├── context.rs
    │   │   ├── mod.rs
    │   │   └── signer.rs
    │   ├── json
    │   │   ├── client_state.json
    │   │   ├── client_state_proof.json
    │   │   ├── consensus_state.json
    │   │   ├── consensus_state_proof.json
    │   │   └── signed_header.json
    │   └── mod.rs
    ├── fixture.rs
    └── mod.rs

Remark

• The mock types are still maintained within the ibc crate.
• This PR also solves the issue reported here: cargo test fails with no-default-features #770. But keeping that issue open for adding something to CI as well.

---

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

Attention: 156 lines in your changes are missing coverage. Please review.

Comparison is base (527bb14) 67.72% compared to head (3f5741e) 66.39%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #954      +/-   ##
==========================================
- Coverage   67.72%   66.39%   -1.33%     
==========================================
  Files         130      161      +31     
  Lines       16491    15770     -721     
==========================================
- Hits        11168    10470     -698     
+ Misses       5323     5300      -23     

Files	Coverage Δ
crates/ibc-derive/src/utils.rs	95.38% <100.00%> (ø)
crates/ibc-testkit/src/hosts/block.rs	92.72% <100.00%> (ø)
crates/ibc-testkit/src/relayer/context.rs	73.07% <100.00%> (ø)
crates/ibc-testkit/src/relayer/error.rs	0.00% <ø> (ø)
...it/src/testapp/ibc/applications/transfer/module.rs	100.00% <100.00%> (ø)
...stkit/src/testapp/ibc/clients/mock/client_state.rs	94.86% <100.00%> (ø)
...it/src/testapp/ibc/clients/mock/consensus_state.rs	93.10% <100.00%> (ø)
...ibc-testkit/src/testapp/ibc/clients/mock/header.rs	77.21% <100.00%> (ø)
...stkit/src/testapp/ibc/clients/mock/misbehaviour.rs	88.88% <ø> (ø)
...tes/ibc-testkit/src/testapp/ibc/core/client_ctx.rs	87.19% <100.00%> (ø)
... and 88 more

... and 4 files with indirect coverage changes

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[rnbguy]

Thanks @Farhad-Shabani for taking care of this big PR. Just a few suggestions and questions.

[rnbguy]

Just few more comments 🙂 Otherwise, I approved the PR.

This was a huge effort ! Thanks @Farhad-Shabani 🙏