0.37-RC2: disable Done button in cases where click behavior target isn't specified

[mazameli]

Related to #13405, we should be smarter about preventing users from clicking Done in cases where they are in fact not done.

Cross filtering

Done should be disabled here until you pick a target parameter; this behavior doesn't do anything otherwise.

URLs

We should probably add a Cancel button here, and at least disable Done until it has something in it:

Making the above changes to the modal should in theory prevent this state, but Done should be disabled in this state where my URL is blank:

Saved question/dashboard as destination

We should disable Done if no question/dashboard has been selected: