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/tests/test-window/CMakeLists.txt

@@ -0,0 +1,11 @@
+set(SOURCES
+	main.cpp
+)
+
+add_executable(test-window ${SOURCES})
+banan_include_headers(test-window ban)
+banan_include_headers(test-window libinput)
+banan_link_library(test-window libc)
+banan_link_library(test-window libgui)
+
+install(TARGETS test-window OPTIONAL)