PowerToys [runner]Fix triggering non-set hotkeys

Summary of the Pull Request

Apparently, left-clicking Slack systray icon sends None (vkCode = 0) keyboard input. As all of the modifier keys are false (if not pressed) this is the same as key combination as default non-set Hotkey{}. therefore, whatever non-set hotkey was not set - was triggered.

PR Checklist

[x] Closes: #32971
[ ] Communication: I've discussed this with core contributors already. If 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 for new binaries
- [ ] WXS for installer for new binaries and localization folder
- [ ] YML for CI pipeline for new test projects
- [ ] YML for signed pipeline
[ ] Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

Without this fix:

Copy some text
Left click slack systray icon and observe that text is pasted into slack input text box

With the fix:

Follow the same steps and observe that nothing is pasted into slack