Feature: Type text in search box only show match string

1. Type the text in the search box
<img width="960" alt="image" src="https://github.com/riophae/vue-treeselect/assets/31730550/da612c73-cc53-47cc-b3f6-93a9a23556d4">
2. Suppose type"Fruits"
  only match a complete string or leading character sequences;
  ft->not ok
  fr->fine
  ru->not ok