Suggest servers to trust based on existing federated shares

[MorrisJobke]

• from Nextcloud 12 overview #2672
• in the federation section show suggestions for trusted servers based on received/send shares sorted by usage stats

cc @schiessle @jancborchardt

[jancborchardt]

Yup. Interface-wise they could be shown as ghost-entries on the bottom of the trusted servers list with opacity: .5; and a button »Add as trusted« to the right of it.

Sounds good @schiessle?

[MorrisJobke]

Most likely nothing for 14 -> moving to 15.