UI: Match Windows taskbar state to tray icon

This adds a status icon for active/paused outputs.

Stripped down version of #2442

UI/CMakeLists.txt

@@ -73,6 +73,9 @@ find_package(Threads REQUIRED)
 find_package(Qt5Network ${FIND_MODE})
 find_package(Qt5Widgets ${FIND_MODE})
 find_package(Qt5Svg ${FIND_MODE})
+if(WIN32)
+	find_package(Qt5WinExtras ${FIND_MODE})
+endif()
 find_package(Qt5Xml ${FIND_MODE})
 
 find_package(FFmpeg REQUIRED COMPONENTS avcodec avutil avformat)
@@ -447,6 +450,8 @@ if(WIN32)
 	set_target_properties(obs
 		PROPERTIES
 			OUTPUT_NAME "obs${_output_suffix}")
+	target_link_libraries(obs
+			Qt5::WinExtras)
 endif()
 
 target_link_libraries(obs