[SelectionList Improvements][Phase 1] Create `SelectionList` Component

[grgia]

Part 1 from #65212

1. Create SelectionList (without data sections)

Description:

Implement a new list component using FlashList to support flat arrays (single-section only). This will serve as a simpler and more performant alternative to SelectionList for the ~80% of use cases that don’t use sections.

• New list component using FlashList
• Supports flat arrays (single-section only)

Issue Owner

Current Issue Owner: @zfurtak

[melvin-bot]

@grgia, @zfurtak Whoops! This issue is 2 days overdue. Let's get this updated quick!

[zfurtak]

Working on the component

[melvin-bot]

@grgia, @zfurtak Uh oh! This issue is overdue by 2 days. Don't forget to update your issues!

[zfurtak]

Hi 👋 I'm working on the component. Here's a draft PR, but it still needs a bunch of work
I'm making progress, though 🚀

[grgia]

Thank you!