build: Provide initial meson infrastructure

Define the starting points for the libcamera build using
meson and ninja build components.

An initial 'dummy' library class is created, and a test binary links
against the shared library calling it's init_lib() function.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera.h

@@ -0,0 +1,5 @@
+class libcamera
+{
+public:
+	void init_lib(void);
+};