Don't glom new tabs into the _quake window

[Niu Shuai (niushuai1991)]

Summary of the Pull Request

When windowingBehavior is set to useExisting or useAnyExisting, new terminal instances glom into the most recently used window. Since pressing Win + ` activates the _quake window, it is almost always the most recently used one — so new tabs ended up inside the quake dropdown, where the tab row is not visible and tabs cannot be switched.

This PR restores the old semantics: the _quake window is never treated as the MRU glomming target.

References and Relevant Issues

• Exempt the _quake window from glomming #9956 originally made the Monarch skip the _quake window when picking a glomming target
• This fixes summoning _quake as the MRU window #10108 parameterized that exclusion so summoning kept working
• Remove Monarch/Peasant & Make UI single-threaded #18215 removed the Monarch/Peasant layer and the exclusion was lost — this regression exists ever since
• Resolves New instance use Quake Mode window #20190 (verified as the same bug; the issue is still open with no linked PR)

Detailed Description of the Pull Request / Additional comments

WindowEmperor::_mostRecentWindow() gains an ignoreQuakeWindow argument:

• glomming passes true, so _quake is skipped as a target:
  • WindowingMode::UseAnyExisting in _dispatchCommandline
  • the per-virtual-desktop MRU loop and its no-virtual-desktop fallback in _dispatchCommandlineCurrentDesktop
• summoning passes false, so globalSummon and the notification area still summon the quake window when it is the MRU one
• _dispatchSpecialKey also passes false, unchanged behavior when the quake window is focused
• wt -w _quake still targets the quake window explicitly via GetWindowByName

Validation Steps Performed

All tested manually with a local build:

1. useAnyExisting: open a regular window, summon quake via Win + ` (making it the MRU window), then launch a new instance → the new tab gloms into the regular window, not the quake window (before this change it went into the quake window)
2. useExisting (per-virtual-desktop path): same steps, same result
3. With only the quake window left open, launching a new instance correctly creates a new regular window instead of glomming into quake or failing
4. wt -w _quake still creates a new tab in the quake window
5. Win + ` still summons/dismisses the quake window repeatedly, with its session content preserved
6. Keyboard input and shortcuts still work while the quake window is focused

PR Checklist

• Closes New instance use Quake Mode window #20190
• Tests added/passed
  • (no unit tests cover WindowEmperor's window-picking; validated manually per the steps above)
• Documentation updated
  • If checked, please file a pull request on our docs repo and link it here: #xxx
• Schema updated (if necessary)

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[Niu Shuai (niushuai1991)]

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