chore: Add app layout toolbar internal component

[just-boris]

Description

Adding new version of app layout to the mainline to avoid permanent rebases

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

How has this been tested?

Currently, only Typescript build. Making existing app layout tests passing against all design variants will be a separate task

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`](https://github.com/cloudscape-design/components/blob/main/CONTRIBUTING.md#public-apis)._ - _Changes do not include unsupported browser features, see [`CONTRIBUTING.md`](https://github.com/cloudscape-design/components/blob/main/CONTRIBUTING.md#browsers-support)._ - _Changes were manually tested for accessibility, see [accessibility guidelines](https://cloudscape.design/foundation/core-principles/accessibility/)._ #### Security - _If the code handles URLs: all URLs are validated through [the `checkSafeUrl` function](https://github.com/cloudscape-design/components/blob/main/src/internal/utils/check-safe-url.ts)._ #### Testing - _Changes are covered with new/existing unit tests?_ - _Changes are covered with new/existing integration tests?_

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[codecov[bot]]

Codecov Report

Attention: Patch coverage is 96.95817% with 8 lines in your changes missing coverage. Please review.

Project coverage is 95.62%. Comparing base (e1c0652) to head (9775324).

Files	Patch %	Lines
...app-layout/visual-refresh-toolbar/drawer/index.tsx	89.28%	3 Missing :warning:
...layout/visual-refresh-toolbar/navigation/index.tsx	84.61%	2 Missing :warning:
src/app-layout/visual-refresh-toolbar/index.tsx	98.61%	1 Missing :warning:
...visual-refresh-toolbar/toolbar/drawer-triggers.tsx	97.72%	1 Missing :warning:
...pp-layout/visual-refresh-toolbar/toolbar/index.tsx	95.23%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2374 +/- ## ========================================== + Coverage 95.49% 95.62% +0.12% ========================================== Files 708 720 +12 Lines 18887 19143 +256 Branches 5998 6435 +437 ========================================== + Hits 18037 18306 +269 + Misses 842 783 -59 - Partials 8 54 +46 ```

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[johannes-weber]

General: When testing the app dev pages (with ?appLayoutWidget=true), there is a strange behaviour with the grid when switching to mobile -

https://github.com/cloudscape-design/components/assets/569011/4a90a5c1-ff04-424f-8001-32464043cb13

Steps to reproduce:

• open this app layout test page
• narrow the viewport width down to <= 688px