Simple 9 key keyboard in example-project directory

[seveibar]

This will be a good circuit for testing that the CLI works properly

[homie-gg]

Here are some pull requests that might be helpful reference for this task:

• Mega Refactor: Reorganize into single package.json, fix all types, improve imports, improve organization

[homie-gg]

This might have already been done via: 9key macrokeypad part 2, improve entrypoint file error reporting.

[homie-gg]

This might have already been done via: Possible fix for traces switching layers accidentally, cleanup trace code, add test for 9 key keyboard.

[homie-gg]

This might have already been done via: Update 3d viewer, core and pcb viewer. Add switches to keyboard example.