chore: Custom button for AI panel's exit expanded mode

[georgylobko]

Description

Introduced a new api method to replace a standard exit expanded mode button for the AI panel

registerLeftDrawer({
  ...,
  exitExpandedModeTrigger: {
    customIcon: `
      <svg width="94" height="24" viewBox="0 0 94 24" fill="none" focusable="false" aria-hidden="true">
        <rect width="94" height="24" rx="4" fill="url(#paint0_linear_145_32649)"/>
      </svg>
    `,
  },
});

Related links, issue #, if available: n/a

How has this been tested?

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

---

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.16%. Comparing base (e06d3c4) to head (a9c8473).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3940   +/-   ##
=======================================
  Coverage   97.16%   97.16%           
=======================================
  Files         854      854           
  Lines       24969    24978    +9     
  Branches     8794     8799    +5     
=======================================
+ Hits        24260    24271   +11     
+ Misses        702      701    -1     
+ Partials        7        6    -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[just-boris]

To reuse number of no-danger exceptions, can we create a reusable utility customTriggerIcon and reuse it for both triggers?

Even if it is one line, at least it confines the eslint exception in one place

[just-boris]

Why is this ReactNode? We do not use it on the other triggers because it does not work in micro-frontends, so we also don't do it here

[georgylobko]

This customIcon type is what we get after processing the runtime data. The actual plugin api only works with strings

[just-boris]

OK I see, there is a string in src/internal/plugins/widget/interfaces.ts update