[WIP][TASK] Add extension:list command

This Introduces a new commandController for listing all available extensions.

What's planned:
[x] list as text
[ ] list as json
[ ] list by state (active/inactive)
[x] list in detail or plain
[ ] list by local or system extension

Where x indicates done.

Execute by using the ``extbase builder:list (--detail)`` command.

THIS IS WIP!