picker(git_branch): show committer, upstream and date (#695)

* wip: rich finder for branches

for: https://github.com/nvim-telescope/telescope.nvim/issues/569

* fix some diagnostics

lua/telescope/pickers/highlights.lua

@@ -43,7 +43,7 @@ end
 function Highlighter:clear_display()
   if not self
       or not self.picker
-      or not self.picker.results_bufnr 
+      or not self.picker.results_bufnr
       or not vim.api.nvim_buf_is_valid(self.picker.results_bufnr)
         then
     return