Constraints on uncommitted machines should be visible (and editable)

[johnsca]

When an uncommitted machine is pending, any constraints specified are not visible. It would also be nice if the pending constraints could be modified in place without removing the pending machine entirely and re-assigning the unit to a new machine (having to specify all of the constraints from scratch, rather than making just the changes that are needed).

This is most useful when tweaking a bundle just prior to deployment.

[hatched]

Hi @johnsca thanks for bringing this up, this would be a great feature to add! I'll bring it up to the rest of the team and see what we can come up with.

Related #1379

[kasiag]

adding @cassiocassio