Allow a lambda for the other param to where

[max-sixty]

Is your feature request related to a problem?

Currently we allow:

da.where(lambda x: x.foo == 5)

...but we don't allow:

da.where(lambda x: x.foo == 5, lambda x: x - x.shift(1))

...which would be nice

Describe the solution you'd like

No response

Describe alternatives you've considered

I don't think this offers many downsides — it's not like we want to fill the array with a callable object.

Additional context

No response

[max-sixty]

#8256