add dora C++ node for ZED stereo camera capture

Implements a dora-rs node that captures frames from ZED cameras
and publishes BGR images, XYZRGBA point clouds, and camera
intrinsics. Includes CMake build system with automatic dora-rs
C++ bindings, dataflow definition, and documentation.

dataflow.yml

@@ -0,0 +1,11 @@
+nodes:
+  - id: zed-camera
+    git: ssh://git@gitea.liria.cl:5001/liria/dora-zed.git
+    build: mkdir -p build && cd build && cmake .. && make install
+    path: bin/dora_zed
+    inputs:
+      tick: dora/timer/millis/100
+    outputs:
+      - image_bgr
+      - point_cloud
+      - camera_info