Add SaveMap service and improve depth settings for mapping

[felipesanmartin]

📝 Description

This PR adds support for saving the Spatial Mapping point cloud to a file through a dedicated ROS2 service. This enables users to persist the generated 3D map without needing to manually capture or reprocess the data from runtime streams. The change is implemented as a non-breaking feature and is intended to improve usability for offline processing, debugging, and map export workflows.

I had to modified zed-ros2-interfaces too to add the new service definition. I added my fork as submodule, but it should be removed if my changes are accepted in that repository and release as new version of zed_msgs.

🔗 Related Issues / Tickets

A related issue is 295, an user ask for this functionality.

🚀 Type of Change

• ✨ New feature (non-breaking change which adds functionality)

🧪 How Has This Been Tested?

• Manual Verification: Steps taken to verify visually or functionally.

  1. Built the ZED ROS2 wrapper and interfaces after the code changes.
  2. Launched the ZED camera node with Spatial Mapping enabled.
  3. Triggered the new SaveMap service from ROS2. (ros2 service call /zed/zed_node/save_map zed_msgs/srv/SaveMap "{map_filename: "test_srv", file_format: 0}")
  4. Verified the service call succeeds without runtime errors.
  5. Confirmed that the point cloud/map file is created at the requested path.
  6. Checked that the generated file is readable and contains valid map data.

⬜ Pre-Merge Checklist

• My code follows the style guidelines of this project.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings or console errors.