toggled Swagger UI representation in spec designer

[jackkav]

changelog(Improvements): Add back UI preview mode alongside OpenAPI/Swagger spec editor

Goal: bring back swagger ui preview as a closable window alongside the spec editor.

Approach: attempt to use swagger-ui-dist to avoid coupling the app to swagger-ui dependency versions.

Result:

• adds swagger-ui-dist to node_modules increasing total size by 9.6M
• manages lifecycle with a useeffect triggered on spec contents changes, or toggle button conditional render

Issues:

• doesn't support theming, never did
• was previously hardcoded to dark mode, now its hard coded to light since the dark mode was more custom css to maintain
• root loader is running sync functions on every fetch with a half second debounce, which runs in this component every key press which means updates to the swagger ui run afterwards, this could be problematic to timing issues

Closes INS-2566