Feat: Better multicore connection

[Tiwalun]

This is not yet final, just for feedback.

This adds a new Configuration struct, which can be used to select the cores for a Session. This is helpful for chips where one of the cores could be locked, or otherwise not accessible for debugging, so that it's still possible to work with the other core(s).

[diondokter]

I like that the core selector can be both an index or a name :)

[Yatekii]

What's the status on this? :)