Iframe interface not available in PreviewBlock in ui-kit

[Vinayak Sharma]

Currently the block which supports oembed in apps engine https://github.com/RocketChat/fuselage/blob/develop/packages/ui-kit/src/blocks/layout/PreviewBlock.ts is for images only. How we could we make UI block to support oembed block with iframes in apps-engine similar to how embeddable links are handled in Rocket.Chat

This issue is because of problem I am facing in integrating whiteboard oembed for Whiteboard Integration for GSoC'23.
@d-gubert @sampaiodiego @tapiarafael your guidance will be really helpful.