(nvim): Import nvim configuration

[mrolli]

Is your feature request related to a current shortcoming? Please describe.
Having dotfiles in one place makes it easier. Still not sure if I actually
should do it. Is the nvim configuration its own project? Previously maybe, but
now with LazyGit it's not anymore. Slimmer and not that bloated anymore. Feels
more like "just some config changes but over all out of the box".

Describe the solution you'd like
Just copy over the configuration after getting rid of stow. Do we need the
history? Nah, not really.

Describe alternatives you've considered
Investigate for an easy way to port the commit history. Might still be worth it.
But the clean it up and take over as few commits as possible.

[mrolli]

Importing a repo including its history is actually quite easy:

https://stackoverflow.com/questions/1425892/how-do-you-merge-two-git-repositories

[mrolli]

The repo nvim.config repository has been been imported into the subdirectory
nvim, see ae6c00987b4e496d3ff679619a793524126619c8.