[CmdPal] Close Gracefully (#39589)

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fix/what does it change/how was it tested (even manually, if necessary)?
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## Summary of the Pull Request

CmdPal is leaking extensions processes as the process is immediately
killed.
This PR fixes the 1.5s wait for the process to end correctly and also
close extensions.

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## 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](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

<!-- Describe how you validated the behavior. Add automated tests
wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

- Verified that if CmdPal closes in 1.5s, extensions and process are
closed (note that GitHub extension doesn't close probably due to
https://github.com/microsoft/PowerToys/pull/39209)
- Verified that if CmdPal doesn't close in 1.5s the process is killed
and extensions aren't closed (tested adding a delay in the code)

src/modules/cmdpal/CmdPalModuleInterface/dllmain.cpp

@@ -117,16 +117,18 @@ private:
 
         for (DWORD pid : processIds)
         {
-            HANDLE hProcess = OpenProcess(PROCESS_TERMINATE, FALSE, pid);
+            HANDLE hProcess = OpenProcess(SYNCHRONIZE | PROCESS_TERMINATE, FALSE, pid);
 
             if (hProcess != NULL)
             {
                 SetEvent(m_hTerminateEvent);
 
-                // Wait for 1.5 seconds for the process to end correctly and stop etw tracer
-                WaitForSingleObject(hProcess, 1500);
+                // Wait for 1.5 seconds for the process to end correctly, allowing time for ETW tracer and extensions to stop
+                if (WaitForSingleObject(hProcess, 1500) == WAIT_TIMEOUT)
+                {
+                    TerminateProcess(hProcess, 0);
+                }
 
-                TerminateProcess(hProcess, 0);
                 CloseHandle(hProcess);
             }
         }

src/modules/cmdpal/Microsoft.CmdPal.UI/App.xaml.cs

@@ -67,6 +67,7 @@ public partial class App : Application
             "Local\\PowerToysCmdPal-ExitEvent-eb73f6be-3f22-4b36-aee3-62924ba40bfd", () =>
             {
                 EtwTrace?.Dispose();
+                AppWindow?.Close();
                 Environment.Exit(0);
             });
     }