[Figma Bridge] Make it easier to skip/unskip multiple elements

Currently, skipping multiple elements requires one of:

• Selecting each Frame/Component individually and marking them "Export as"="Skipped" (this is very tedious), OR
• Putting multiple elements inside a Group and skipping that group (this changes the structure of the project)

Use-case

Customer has a large Figma project with many pages, where many elements are WIP. They want to prevent the non-ready elements from being exported for now.

Idea

Perhaps we can allow skipping everything in a Page? Figma lets us detect page changes: https://www.figma.com/plugin-docs/api/properties/figma-on/#currentpagechange