Feature: Backend for dropbar.nvim

[willothy]

Original mention here.

Since dropbar.nvim supports vim.ui.select, we should implement a dressing.nvim backend for it to make integration for users easier.

This would be great to have, I will get to this as soon as I can :) Mainly creating this issue as a reminder myself to make this happen ASAP. If you consider it a bloat/spam issue because of that, feel free to close and I'll try to remember haha :)