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>

test/init.cpp

@@ -0,0 +1,9 @@
+#include <libcamera.h>
+
+int main(void)
+{
+	libcamera l = libcamera();
+	l.init_lib();
+
+	return 0;
+}