Proposal: move most of the repos as subpackages to CLI

### Why do we need this improvement?

Currently the repos are too granular. We should bring them under a monorepo as subpackages to make stuff easier.

### How will this change help?

- Easier maintainence.
- Faster changes
- Overall less overhead.

### Subpackages

### How could it be implemented/designed?

The following repos are planned for initial:

- server-api: https://github.com/asyncapi/server-api/issues/576
- bundler
- diff
- optimizer

### 🚧 Breaking changes

Yes

### 👀 Have you checked for similar open issues?

- [x] I checked and didn't find a similar issue

### 🏢 Have you read the Contributing Guidelines?

- [x] I have read the [Contributing Guidelines](https://github.com/asyncapi/.github/blob/master/CONTRIBUTING.md)

### Are you willing to work on this issue?

Yes I am willing to submit a PR!