Expose toggleDropdown() function

[sadikerd]

Is your feature request related to a problem? Please describe.
I'm always frustrated when i try to toggle dropdown. I need to be able to open dropdown menu with any props or an exposed function.
This will be used, for instance, couple of vue-select usage and once one is selected, i would like to trigger next vue-select to open immediately its dropdown menu without clicking on it.

Describe the solution you'd like
I saw there is already toggleDropdown() function in Select.vue, maybe this function can be adapted to expose and exposed to external usage. So we can use it like vueSelectRef.value.toggleDropdown()

Describe alternatives you've considered
Maybe implementing a props would be fine.

Additional context
Thanks for such useful components :)