Restructure the ibc crate

[Farhad-Shabani]

Background

This initiative aims to optimize the organization of the ibc crate by decomposing it into smaller, self-contained libraries. A pivotal step in this process involved segregating our mock testing facilities into the standalone ibc-testkit library, as detailed in this PR. By decoupling its implementation from the main ibc crate, we've laid the groundwork for advancing this initiative.

The primary objectives here are twofold: firstly, to diminish the interdependence within the codebase among various components such as ibc core, clients, and applications, and secondly, to elevate the overall usability of the implementation. The overarching aim is to empower users to selectively import specific IBC layers, mitigating potential conflicts related to dependencies or features that may arise in the context of a monolithic library.

Steps

The following steps outline the restructuring process:

Tasks

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1. Write an ADR explaining why this change is necessary and how the codebase will look like afterward
2. Restructure and split off applications module under ibc-apps
3. Restructure and split off light clients under ibc-clients
4. Restructure and split off core module under the ibc-core
5. Define a new library for base types and preludes imported by other crates
6. Move main directories/libraries to the root of the repository, eliminating the need for the /crates directory.
7. Expose different consts, types and impls for public access #976
   O: usability +1
   

Next

Following the above steps, the next phase involves preparing a GitHub action for streamlining the release process:

• Add GitHub Action to automate release process #983

Checklist

Additionally, for each added library, we should adhere to the following checklist:

• Use workspace dependency
• Remove unused dependencies and feature flags
• Add a README and short description for each library
• Update the main README page
• Update the Releases section of contributing.md
• Reflect changes on basecoin-rs

Relevant issues

• Move transfer application and tendermint client to separate crates #716
• [ICS24] Discard Default impl for ClientId and move away from tm_client_type in unit tests  #552