Improve Backup Info view controller

For multisig accounts we ought to more clearly associate each “part” of an m of n setup with the location of its seed or xprv. Clearly communicating that x xpub belongs to the node and y xpub to the device and so on, so that a user understands where the seeds are located.

Instead of grouping seeds and xpubs together we ought to list groups, each group containing the location, an optional label, the xprv, xpub, path, fingerprint and seed for each extended key.

We should also add an explanation for the change keys so a user understands there is a separate path for change.