[ENH]: Prepare Junifer for extension support

[fraimondo]

Are you requiring a new dataset or marker?

• I understand this is not a marker or dataset request

Which feature do you want to include?

If I install junilog or junifer-data, I would like to call them using junifer log or junifer data, through the junifer click group.

How do you imagine this integrated in junifer?

1- On importing junifer, we "import and register all extensions"
2- Each extensions provides a "group name" and registers this group under the junifer click group.

Do you have a sample code that implements this outside of junifer?

No response

Anything else to say?

No response