[Workspaces] launch same apps sequentially

[donlaci]

Summary of the Pull Request

If there are multiple instances of the same app, Workspaces will launch them sequentially, waiting for each new instance to appear befor launching a new instance. It is needed for example for MS Outlook

PR Checklist

• Closes: #xxx
• 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

Tested locally

[SeraphimaZykova]

With this approach, it doesn't work as intended and it's unsafe.
You're accessing m_needAdditionalLaunch from different threads, potentially leading to a crash.

[SeraphimaZykova]

Closing in favor of #35297