[PowerAccent] Cancel previous ShowToolbar task if a new one is triggered

[mantaionut]

Summary of the Pull Request

Now cancel the task of ShowToolbar if another is started,

PR Checklist

• Closes: Normal typing with space set as the Quick Accent activation key sometimes results in space characters moving one character late. #35803
• 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

ShowToolbar would start a task with the delay of the normal input delay, this is an issue since if you release the activation key and then press it again a new task would be created, then the previous task could end and show the toolbar. This creates scenarios where showing of the toolbar is not always at the same time.

Validation Steps Performed

Tested by using 300ms delay.
Tested by using 5000ms delay. Hold the spacebar for 3 seconds release and then hold it again for 5 seconds. Previously the taskbar would be triggered at the second hold after holding it for 2 seconds, Now it is shown after holding it for 5 seconds.