refactor: convert Scrollable to TypeScript

[wgu-taylor-payne]

Description

Converts the Scrollable component from JSX to TypeScript.

Part of issue #3739.

Changes

• Converted src/Scrollable/index.jsx to index.tsx
• Created ScrollableProps interface with JSDoc comments for prop documentation
• Removed deprecated propTypes and defaultProps
• Added displayName for docs generation
• Updated src/index.ts to remove @ts-ignore and move Scrollable to typed exports section

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Co-authored-by: Amazon Q no-reply@amazon.com

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.39%. Comparing base (dfc69e2) to head (084eae3).
⚠️ Report is 7 commits behind head on release-23.x.

Additional details and impacted files

@@              Coverage Diff              @@
##           release-23.x    #4135   +/-   ##
=============================================
  Coverage         94.39%   94.39%           
=============================================
  Files               242      242           
  Lines              4296     4299    +3     
  Branches           1020     1020           
=============================================
+ Hits               4055     4058    +3     
  Misses              237      237           
  Partials              4        4           

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