CSS Modules: convert remaining activity components to CSS modules

[OEvgeny]

Fixes #

Changelog Entry

• Converted remaining activity components to CSS Modules, in PR #5668, by @OEvgeny

Description

This PR converts remaining components in the component/src/Activity folder to CSS modules.

• I have added tests and executed them locally
• I have updated CHANGELOG.md
• I have updated documentation

Review Checklist

This section is for contributors to review your work.

• Accessibility reviewed (tab order, content readability, alt text, color contrast)
• Browser and platform compatibilities reviewed
• CSS styles reviewed (minimal rules, no z-index)
• Documents reviewed (docs, samples, live demo)
• Internationalization reviewed (strings, unit formatting)
• package.json and package-lock.json reviewed
• Security reviewed (no data URIs, check for nonce leak)
• Tests reviewed (coverage, legitimacy)