feat: Build vim colorscheme file colors/boo.vim

[rockerBOO]

This makes the colorscheme have 2 supported uses.

colorscheme boo 

will use the boo.vim with the exported colors

lua require('boo-colorscheme').use({})

will use the lua version of the colorscheme.

This allow us to support vim with this colorscheme as well as neovim.

[rockerBOO]

The problem with the approach is colors/boo.vim get sourced before or instead of colors/boo.lua. This hurts making this colorscheme support Vim as well as I can not have both files there. Maybe I can short circuit if Neovim is the runtime.