Expand panel shutdown event listener to all platforms

[WizardCM]

Description

This expands the previously introduced shutdown loop check for browser docks to Windows and macOS.

As a reminder, this solves a potential crash on shutdown if the user has many docks or heavy docks.

As this solution has a timeout (max 1 second per dock), I am much more comfortable expanding its usage to all platforms compared to the original solution.

Motivation and Context

I have a feeling that users on other platforms have been running into this issue, but because we don't provide CEF symbols (and because it occurs on shutdown) reports have been sporadic and/or lacking the necessary detail to track it down.

How Has This Been Tested?

Close browser docks manually and on shutdown, experience no crash.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.