[SG-33416] Improve discoverability of the storybook preview link

Created by: gitstart-sourcegraph

Description

• Shell script to get Storybook preview url from Chromatic publish output and add it into App Preview section in PR description

Test plan

Make sure all checks are passed in CI

Refs

• SourceGraph Issue
• GitStart ticket

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.