[2.0.x] Move pattern_preview render element to ui_patterns_library

Built on top of !30 from 📌 [2.0.x] Remove unused escape property from Field definitions Fixed

The 2.0.x branch has changed since the last commit but this issue's goal is still met:

• component_story, the successor of pattern_preview, has be placed in ui_patterns_library as expected
• pattern_preview, has been moved to ui_patterns_legacy