feat: add signify support

[bobbleclank]

Both Git Gutter and Git Signs are supported. This pull request adds support for Signify.

Without Signify support a workaround like the following is required.

function! TokyonightThemeHighlighting()
  highlight SignifySignAdd    guifg=#399a96
  highlight SignifySignChange guifg=#6382bd
  highlight SignifySignDelete guifg=#c25d64
endfunction

augroup TokyonightThemeAutoCommands
  autocmd!
  au ColorScheme tokyonight,tokyonight-storm,tokyonight-night,tokyonight-moon
               \ call TokyonightThemeHighlighting()
augroup END

[dsummersl]

would love to see this in here...for now I just stuck it in my config:

  {
    "folke/tokyonight.nvim",
    init = function()
      -- vim.cmd.colorscheme('tokyonight')
    end,
    config = function()
      vim.cmd([[
        function! TokyonightThemeHighlighting()
          highlight SignifySignAdd    guifg=#399a96
          highlight SignifySignChange guifg=#6382bd
          highlight SignifySignDelete guifg=#c25d64
        endfunction

        augroup TokyonightThemeAutoCommands
          autocmd!
          au ColorScheme tokyonight,tokyonight-storm,tokyonight-night,tokyonight-moon
                       \ call TokyonightThemeHighlighting()
        augroup END
      ]])
    end,
    lazy = false,
    priority = 1000,
    opts = {},
  },