feat: add keybinds to go to next/prev commit in File History

[marcomayer]

When opening :CodeDiff history % for example, I see the bottom panel of commits but I didn't find a way to bind keymaps to goto next/prev commit while being in an actual file. Would be a great addition even though it's a minor one.

[chek1337]

I will complete the suggestion.
For example, use Ctrl+N/Ctrl+P to scroll through the list in Explorer (this already partially works). And use Ctrl+F/Ctrl+B to scroll through the buffers (for example, how it is implemented in diffview.nvim).

I would also like to see a button that allows you to quickly scroll through and open the changes for viewing, file by file, for example, the Tab button.

[fredrikaverpil]

@esmuellert is it just me, or does this only work if you first manually expand the commits?

[fredrikaverpil]

I added a PR in #212 which illustrates auto-expansion which allows for simply hitting ]f and [f (or whichever keymap you have) to move between commits seamlessly.

[marcomayer]

@esmuellert great thanks! For me the highlighting didn't work when switching files, I opened a PR to fix this: #213