CmdPal: Make Dock stay on top of all other windows (#46163)

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fix/what does it change/how was it tested (even manually, if necessary)?
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## Summary of the Pull Request

This PR makes Dock stay on top of all other windows:

- Marks the Dock window as topmost when there is no full-screen window.
- Adds a new option that allows the user to disable this behavior.
- Adds a timer that polls the system API to determine whether a
full-screen window is present.

## Pictures? Pictures!

<img width="560" height="283" alt="image"
src="https://github.com/user-attachments/assets/55346005-2fac-4357-88bd-60c899565fac"
/>



https://github.com/user-attachments/assets/b81bff6d-4616-4d17-a1b0-063d254022ed


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## PR Checklist

- [x] Closes: #46161
<!-- - [ ] 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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## Detailed Description of the Pull Request / Additional comments

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## Validation Steps Performed