Show arrow on dropdown

Is your feature request related to a problem?

It's impossible to discern a Dropdown from a normal Button

Describe the solution you'd like:

I'd like to have an arrow pointing downwards on the dropdown, showing that you can display more options.

I believe this is related to code in

Orchestra/spinner/src/main/kotlin/com/skydoves/orchestra/spinner/SpinnerCompose.kt

Line 150 in 025385f

setShowArrow(false)

As it has a setArrow boolean, which is not present in the list of parameters. If it is really a 'should I display a dropdown arrow' we should add it to the composable funcion