Include "packages" as submodules

[kkmuffme]

Feature Request

• Yes, I reviewed the contribution guidelines.

Describe your use case and the problem you are facing

Currently, it requires:

Before you can proceed further, you'll need to make sure you have Composer, PHP, and a functioning MySQL or MariaDB server on your local machine.

However, for many use cases none of those are technically required and additionally unnecessary overhead is added by installing it via composer and workflows sometimes unnecessary complicated bc of that too.

Describe the solution you'd like

Optionally (actually I'd even say as the default) include the wp-cli packages as submodules instead of loading them from composer.
This gets rid of all the required dependencies (no composer, no PHP and no db needed).

[swissspidy]

The current Composer approach allows us to easily symlink all the dependencies so that there is a single vendor folder for all the packages in the repository root. Would Git submodules allow for the same?

Personally I found submodules always very cumbersome to use, and Composer is a requirement for contributing to WP-CLI (run tests etc.)

This gets rid of all the required dependencies (no composer, no PHP and no db needed).

How would you want to contribute to WP-CLI without PHP or even Composer?