Opening a ".tscn" file in Search Results should open the scene

[KoBeWi]

Godot version:
3.2 beta3

Issue description:
You can add .tscn files to possible search filters for Search in Files (useful for built-in-scripts) and they show correctly and all, but when you click the result, it opens the scene... as text in Script Editor. It would be more useful if it opened it as scene, not text.

Somewhat related to #20692