feat(view): floating window's optional adaptive size specification (#1559)

lua/nvim-tree/view.lua

@@ -246,7 +246,8 @@ function M.grow_from_content()
 end
 
 function M.resize(size)
-  if M.View.float.enable then
+  if M.View.float.enable and not M.View.adaptive_size then
+    -- if the floating windows's adaptive size is not desired, then the
     -- float size should be defined in view.float.open_win_config
     return
   end