feat(devx): Developer.md discovery system

[apskhem]

This feature makes devx to discover all Developer.md files with a project.

[jmgilman]

So, for this feature, you'll want to tie into the existing project discovery mechanism.

• Project's are defined here
  • Notice how project's already define an Earthfile field (set to a pointer since it's optional)
• The project loader is responsible for loading projects
  • All you need is the root path to the project
  • As an example, this is where the loader checks for and optionally parses an Earthfile
• There is also a project scanner in the CLI code
  • You can see an example of it being used here

Those should be the components you need for the devx command. Bear in mind that a lot of this logic already has unit tests. So you'll need to modify them with any logic you add. This necessarily means you'll need to make sure you keep the existing code testable. If you have any questions about that, let me know.

What I would propose is:

1. Add logic to check for and parse a developer.md in the project loader
2. Modify the devx command to use the project scanner for finding all projects
3. Once you have a list of projects, you can filter it down to list only projects that had a developer.md file