Feat: branch to show string instead of disabling

[daUnknownCoder]

Requested feature

if im not in a git repo, the branch is just disabled

i came with this workaround:

        lualine_b = {
          {
            function()
               local is_git = vim.fn.system("git rev-parse --is-inside-work-tree")
               if is_git and vim.v.shell_error == 0 then
                 return vim.fn.system("git branch --show-current | tr -d '\n'")
               end
               return "ungit"
            end,
            icon = icons.git.Branch,
            padding = { left = 2, right = 1 },
          },
        },

which gets me the branch name or ungit but it take too much time to update, like around a few secs after neovim startup which i do not want...

or if the git branch is taking too much time, is there any way to return the component branch from a function?