Initialise applyByModule

[RiboRings]

Hi!

This PR introduces the applyByModule function which provides a way to perform module-wise aka group-wise operations and analyses. Check ?applyByModule for a few example uses.

It's still a draft, but we can discuss here:

• if current implementation looks good
• if mia vs ariadne is the right place to have it
• if name sounds good (applyByGroup and agglomerateByGroup are also nice though)

Cheers,
Giulio