feat: add ability for the tree to change tab

- remove tags file
- open/close the tree on `TabEnter` with the option `g:lua_tree_tab_open`

plugin/tree.vim

@@ -17,6 +17,9 @@ augroup LuaTree
   au VimEnter * lua require'tree'.on_enter()
   au ColorScheme * lua require'tree'.reset_highlight()
   au User FugitiveChanged lua require'tree'.refresh()
+  if get(g:, 'lua_tree_tab_open') == 1
+    au TabEnter * lua require'tree'.tab_change()
+  endif
 augroup end
 
 command! LuaTreeOpen lua require'tree'.open()