build: bundle render worker/backends and fix concurrent param test

- Make olive-editor depend on olive-render-worker on all platforms so the
  worker is always built with the main app.
- Copy olive-render-worker and dynamic render backends (oakgl, oakvulkan)
  into the macOS app bundle next to the executable.
- Include oakgl.dll and oakvulkan.dll in the Windows NSIS installer.
- Fix PluginSmokeThread.ConcurrentParamAccess CI failure by adding a mutex
  around IntegerInstance's no-node fallback storage and serializing the
  test's set/get pair.
- Hide the render worker's Dock icon on macOS via
  NSApplicationActivationPolicyProhibited.

app/packaging/windows/nsis/olive.nsi

@@ -39,6 +39,14 @@ Section "Oak Video Editor"
     SectionIn RO
     SetOutPath $INSTDIR
     File /r olive-editor\*
+
+    # Render worker process must live next to the editor binary
+    File "olive-editor\olive-render-worker.exe"
+
+    # Render backends must also live next to the editor binary
+    File "olive-editor\oakgl.dll"
+    File /nonfatal "olive-editor\oakvulkan.dll"
+
     WriteUninstaller "$INSTDIR\uninstall.exe"
 
     # Install Visual C++ 2010 Redistributable