DevTools+LibGUI: Make ProcessChooser a general Dialog in LibGUI

Moves ProcessChooser and RunningProcessesModel to LibGUI and
generalizes their construction for use by other apps. Updates
Profiler to reflect the change and use its new icons.

DevTools/Profiler/CMakeLists.txt

@@ -1,11 +1,9 @@
 set(SOURCES
     DisassemblyModel.cpp
     main.cpp
-    ProcessChooser.cpp
     Profile.cpp
     ProfileModel.cpp
     ProfileTimelineWidget.cpp
-    RunningProcessesModel.cpp
 )
 
 serenity_bin(Profiler)