Missing unimpaired mapping [p

### Describe your request

This has [already been implemented by evil-collection](https://github.com/emacs-evil/evil-collection/issues/477), but even with evil-collection unpinned I still haven't received the new behavior. Since Doom handles its own implementation of unimpaired, I thought it might be worth raising an issue.

I'm greatly missing the keybinding `[p` for a linewise paste on the previous line, without having to move the cursor there or create a new line.

From unimpaired.txt:

> These are experimental:

*>p* Paste after linewise, increasing indent.
*>P* Paste before linewise, increasing indent.
*

Start by reviewing Doom's unimpaired implementation and compare it with the behavior described in evil-collection issue 477 and unimpaired.txt. Confirm the intended [p, [P, ]p, and ]P linewise paste behavior from the middle of a line, then add coverage or verify the relevant keybindings in an Emacs session.

Written by the indexing model from the issue text.