CmdPal: Add a button to toggle the visibility of the dev ribbon (#45379)

## Summary of the Pull Request

This PR adds an option to toggle visibility of the dev ribbon. The state
is only temporary and does not persist across app runs -- that is
intentional to prevent the dev from turning it off permanently.

<img width="648" height="519" alt="image"
src="https://github.com/user-attachments/assets/c5b348f6-8f3c-4ec2-a250-e051fd003e09"
/>

<img width="1313" height="751" alt="image"
src="https://github.com/user-attachments/assets/89928e30-b0dc-4a14-b5fb-bf68357a145b"
/>


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## PR Checklist

- [x] Closes: #45371
<!-- - [ ] Closes: #yyy (add separate lines for additional resolved
issues) -->
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

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wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

src/modules/cmdpal/Microsoft.CmdPal.UI/Controls/DevRibbon.xaml

@@ -206,9 +206,10 @@
 
                                 <!--  More section  -->
                                 <TextBlock Style="{ThemeResource SettingsSectionHeaderTextBlockStyle}" Text="More" />
-                                <Border>
+                                <StackPanel Orientation="Horizontal" Spacing="8">
                                     <Button Command="{x:Bind ViewModel.OpenInternalToolsCommand}" Content="Open internal tools" />
-                                </Border>
+                                    <Button Command="{x:Bind ViewModel.ToggleDevRibbonVisibilityCommand}" Content="Hide me" />
+                                </StackPanel>
                             </StackPanel>
 
                             <!--  Footer  -->