Fix extra padding by empty flow layout

[compulim]

Fixes #3746.

Changelog Entry

Added

(Updated the entry with PR number)

• Resolves #2745. Added new flow layout to suggested actions, by @compulim in PR #3641 and PR #3748

Description

An unnecessary padding was introduced when using "flow" layout in suggested actions.

Design

Add a flow-box and only show it when there is any suggested actions.

Specific Changes

• Modify SendBox/suggestedActions.js to add a flow-box component
• Modify Styles/suggestedActions.js to move styles to the flow-box
• Add VRT to make sure after a suggested action is selected, the layout is correct

• 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)