BuildSystem: Cleanup userspace directory layout

userspace programs are now in userspace/programs
userspace tests are now in userspace/tests

This makes listing userspace projects much cleaner. Libraries were
already separated to their own directory, so other programs should also.

userspace/programs/WindowServer/CMakeLists.txt

@@ -0,0 +1,16 @@
+set(SOURCES
+	main.cpp
+	Framebuffer.cpp
+	Window.cpp
+	WindowServer.cpp
+)
+
+add_executable(WindowServer ${SOURCES})
+banan_include_headers(WindowServer ban)
+banan_include_headers(WindowServer libgui)
+banan_link_library(WindowServer libc)
+banan_link_library(WindowServer libfont)
+banan_link_library(WindowServer libimage)
+banan_link_library(WindowServer libinput)
+
+install(TARGETS WindowServer OPTIONAL)