feat(resize): add ability to grow and shrink the tree when drawing (#1293)

Will adapt the view size based on the longest line.
fixes #865

doc/nvim-tree-lua.txt

@@ -101,6 +101,7 @@ Values may be functions. Warning: this may result in unexpected behaviour.
       reload_on_bufenter = false,
       respect_buf_cwd = false,
       view = {
+        adaptive_size = false,
         width = 30,
         height = 30,
         hide_root_folder = false,
@@ -418,6 +419,11 @@ Git integration with icons and colors.
 *nvim-tree.view*
 Window / buffer setup.
 
+    *nvim-tree.view.adaptive_size*
+    Resize the window on each draw based on the longest line.
+    Only works when |nvim-tree.view.side| is `left` or `right`.
+      Type: `boolean`, Default: `false`
+
     *nvim-tree.view.hide_root_folder*
     Hide the path of the current working directory on top of the tree.
       Type: `boolean`, Default: `false`