`flip` option does not work in dropdown's configuration

Created by: rohit2sharma95

Setting the flip option to false does not prevent the dropdown from being flipped.

Docs: https://getbootstrap.com/docs/5.0/components/dropdowns/#options Demo: https://jsbin.com/zoviriwovi/edit?html,js,output

Although instead of accepting the boolean value for the flip option it would be good to accept the fallbackPlacements (Without customizing it in Bootstrap's default Popper config) and drop the flip option (Like it is done for tooltip and popover) But it would be a breaking change (In reality it is not breaking since it is not working already) 🤔

/CC @XhmikosR