Add Pending Deals to Sealing Page

[nonsense]

At the moment if the sealing pipeline has no more capacity for new sectors, deals are just blocked in the Adding to sector state, and it is not clear why they are not progressing to the next stage.

We should improve UX around that, so that it is clear that sealing pipeline is operating at capacity, and the new sector will only be created when the existing sectors are done sealing.

[dirkmc]

We should add the "Pending Deals" section from this sketch to the "Sealing Pipeline" page