Update collection cards UI to use non-flat cards

[bjester]

Observed behavior

Studio's channel collections feature uses flat cards. As far as I know, we won't support flat KCard so this design will need to change

On hover:

Expected behavior

We should likely turn these into regular non-flat cards. As a consequence of that, we should move the checkbox outside of the card. Moving the checkbox outside of the card will match the existing design used in the 'Import from channels' modal

User-facing consequences

Inconsistent design experience and UX feedback when the user is hovering on cards.

Additional information

Followup to #4557