refacto: make git module interface to wait for job to finish

allows simplify the explore/reload/find/initialization by making the
whole code synchronous. No more callback needed.

lua/nvim-tree/actions/create-file.lua

@@ -102,9 +102,8 @@ function M.fn(node)
     a.nvim_out_write(file..' was properly created\n')
   end
   events._dispatch_folder_created(file)
-  require'nvim-tree.actions.reloaders'.reload_explorer(function()
-    focus_file(file)
-  end)
+  require'nvim-tree.actions.reloaders'.reload_explorer()
+  focus_file(file)
 end
 
 return M