fix(fn): update Message strip to latest design [ci visual]

[InnaAtanasova]

Related Issue

Part of #3166

Description

• added a new modifier class .fn-message-strip--dismissible for when the message strip is dismissible (has a close button)
• use Nested instead of Layout for the close button of the Message strip
  Before:

<div class="fn-message-strip">
  <span class="fn-message-strip__text">Information (default) Message Strip Text</span>
  <button class="fn-button fn-button--layout fn-button--icon-only fn-message-strip__close-button" aria-label="Close">
    <span class="sap-icon sap-icon--decline"></span>
  </button>
</div>

After:

<div class="fn-message-strip fn-message-strip--dismissible">
    <span class="fn-message-strip__text">Information (default) Message Strip Text</span>
    <button class="fn-nested-button fn-message-strip__close-button" aria-label="close">
        <span class="sap-icon sap-icon--decline"></span>
    </button>
</div>

Screenshots

Before:

After:

[netlify]

✔️ Deploy Preview for fundamental-styles ready!

🔨 Explore the source changes: 0401998

🔍 Inspect the deploy log: https://app.netlify.com/sites/fundamental-styles/deploys/620c026c6c059900079bea29

😎 Browse the preview: https://deploy-preview-3192--fundamental-styles.netlify.app