feat(zcbor): import submodule

We will use CBOR as the serialization mechanism for making IPC
between ocre-cli and ocred.

This is only useful for MPU systems like Linux, and not Zephyr.

Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com>

Author: casaroli

.gitmodules

@@ -8,3 +8,6 @@
 [submodule "tests/Unity"]
 	path = tests/Unity
 	url = https://github.com/ThrowTheSwitch/Unity.git
+[submodule "src/samples/supervisor/posix/zcbor"]
+	path = src/samples/supervisor/posix/zcbor
+	url = https://github.com/NordicSemiconductor/zcbor.git