feat: add vim-dadbod-ui integration

[vihu]

Summary

This adds support for dadbod-ui.

I chose the following colors (mostly because it seemed reasonable):

NotificationInfo = { fg = C.blue, bg = C.mantle },
NotificationWarning = { fg = C.yellow, bg = C.mantle },
NotificationError = { fg = C.red, bg = C.mantle },

PS: There's some whitespace cleanup here as well.

[vollowx]

Thanks for your contribution and patience! ❤️