Add wlr_output_layout implementation

An output layout consists of a mapping of outputs to their position in a global
coordinate system that usually cooresponds to the output position in physical
space in front of the user.

Add an example that allows configuration of an output layout and demonstrates
its boundaries with a bouncing image.

types/meson.build

@@ -2,6 +2,7 @@ lib_wlr_types = static_library('wlr_types', files(
     'wlr_input_device.c',
     'wlr_keyboard.c',
     'wlr_output.c',
+    'wlr_output_layout.c',
     'wlr_pointer.c',
     'wlr_region.c',
     'wlr_seat.c',