chore: refactor CodeExcerpt to a function component

Created by: limitedmage

Part of #34237 (closed)

This was pretty tough to refactor so I would appreciate a thorough review. I had to almost rewrite the whole component due to the heavy use of RxJS and subscription bag.

Test plan

All tests should pass and component should behave the same as before

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.