[Modal Layout Picker] Create Layout Picker category bar UI using static data

[chipsnyder]

Is your feature request related to a problem? Please describe.

This task is part of the effort to rework the Starter Page Template Picker for new pages. This part of the initiative will focus on filling in the category bar in the header using static data that is currently used as part of the existing Starter Page templates.

The end result should look something like:

	iOS	Android
Not Selected
Selected
Scrolled

Goals

• Add the category bar to the header
  • Category cells should be horizontally scrollable
• Category cell should include:
  • Emojis (if provided)
  • Category display name
• Selecting a category should:
  • Update the cell's background
  • Add the checkmark in place of the emoji (or insert a checkmark if no emoji is provided)
  • Deselect any selected categories
  • Hide any category sections that aren't selected
• Dark Mode should be handled for any new UI elements
• Scrolling the layout picker should move the category bar up then "lock" in place once it reaches the top of the screen.
  • Scrolling down should allow the UI to return to the position from when the screen originally loaded.

Additional context

• The static data will be prepared and made available as part of [Modal Layout Picker] Add support for Self-Hosted sites #2455
• This should be worked on after [Modal Layout Picker] Create Modal window for Modal Layout Picker  #2419
• To prepare any static data, the endpoint is being created as part of Add API Endpoint containing the current with starter page layouts #2413. Modeling the static data around the shape of the response created there will help make downstream tasks easier.

Blueprint Flow - iOS

Blueprint Flow - Android