There is an existing user config for setting the winblend value of the
lazygit floating window. This controls the background transparency of
the window. However, this config option is not respected if the lazygit
window is created using plenary (another user config). This change
forces the plenary window to use the existing config for transparency.
Add `LazyGitBorder` and `LazyGitFloat` highlighting groups using nvim(>=0.7.2) function `vim.api.nvim_set_hl`.
Add full list of window border for useful customize.
