option to manually adjust the horizontal padding

The vertical padding between panel in LazyGit appears to be two lines.

The horizontal padding appears to be one character.

I presume this is because both are set to the smallest practical value, to save screen real estate.

But for purely aesthetic reasons, I would like the option of manually overwriting the value for horizontal padding.

I don't yet know whether I would then personally settle on two characters for the width, or three characters because of the `adjust_line_height 4` in my `kitty.conf`. But either way, I would very much value the opportunity to experiment and decide.