refactor(app): Refactor Contributors page from class to functional component

Created by: plibither8

The PR migrates the RepositoryStatsContributorsPage component from class-based to a functional component. Additionally, the PR migrates from using data-tooltip to the new Tooltip component from Wildcard.

Test plan

This PR does not change the app either functionally or visually. The same tests can persist without requiring modifications.

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.