[useMultipleSelection] getDropdownProps doesn't call consumer supplied handlers when preventKeyAction is true

[juzerzarif]

When preventKeyAction is true for getDropdownProps it omits its own onKeyDown and onClick handlers but it also omits any keydown or click handler that the caller may have provided:

https://github.com/downshift-js/downshift/blob/ee2a828ac70035c1e6156523b72c11abae4c07e4/src/hooks/useMultipleSelection/index.js#L211-L214

I think a more predictable behavior would be to call the handlers supplied by the consumer regardless of preventKeyAction (they might have nothing to do with key actions).