feat: Use gitsigns.nvim to display inline diffs
Resolves #39.
Requires: https://github.com/lewis6991/gitsigns.nvim/pull/683
This is an experiment that utilizes gitsigns.nvim to display inline diffs in single window layouts.

What settings are needed to try it out?
@louwers in its current state, this PR is not usable. Buffers flicker when you open entries, the diff highlighting is not always correctly applied unless the buffer is focused, and some unknown condition sometimes causes gitsigns to loose track of the hunks in the buffer, and I haven't really looked into it yet.
Hi @sindrets, any updates on this feature? I see that https://github.com/lewis6991/gitsigns.nvim/pull/683 has been merged.