Add namespace support for uxrce-dds client during firmware upload

[E-Krantz]

Solved Problem

When working with PX4 firmware on hardware, I found it was not possible to set a custom namespace for the uxrce-dds client during firmware upload. This capability existed for SITL via the PX4_UXRCE_DDS_NS environment variable but was not available for hardware builds.

Fixes: No GitHub issue ID

Solution

• Added support for setting a custom namespace for the uxrce-dds client in firmware builds, using the PX4_UXRCE_DDS_NS environment variable—bringing behaviour in line with SITL.
• Updated build logic so that running
  PX4_UXRCE_DDS_NS=vehicle_1 make px4_fmu-v6x_spacecraft
  sets the namespace accordingly during firmware upload.

Note:
A make clean is required before building, to ensure dds_topics.h is regenerated in
build/px4_fmu-v6x_spacecraft/src/modules/uxrce_dds_client/dds_topics.h.

Changelog Entry

For release notes:

Feature: Add optional namespace specification for uxrce-dds client during firmware upload.

Alternatives

None.

Test Coverage

• Tested firmware builds with and without a namespace value on Pixhawk-6X-mini.
• Confirmed that the generated topics reflect the specified namespace.

Documentation

If this PR is accepted, I am happy to update the documentation to reflect the new firmware capability, which currently only describes namespace customisation for SITL.

Context

• This change brings hardware builds to parity with SITL in terms of namespace configuration.

[dakejahl]

This sets the namespace during build time though? I think it would be more useful to have this configurable as a parameter so that it doesn't require a rebuild of firmware

[dakejahl]

Maybe we just need to resurrect this. I would use a unique param for namespace instead of the MAV_SYS_ID
https://github.com/PX4/PX4-Autopilot/pull/21536/files

[E-Krantz]

I can add both alternatives as options, parameter and from terminal.

[beniaminopozzan]

@E-Krantz , have you considered manually starting the client via custom startup script loaded in the SD card (assuming your hardware has a microSD card)?

In that way you don't need a custom build.

I understand that approach has its own drawback too though.

That said, this is a nice addition, thank you!

[E-Krantz]

@beniaminopozzan Thank you for the suggestion. I had not considered that.
What I prefer with this approach is that it aligns with how namespaces are set up in SITL, and it's straightforward for anyone who is using make upload to flash the firmware.
Having more options is great though.

[beniaminopozzan]

@dakejahl I just noticed the failing ci, do you know anything about it? I don't have access to a PC right now

[dakejahl]

@dakejahl I just noticed the failing ci, do you know anything about it? I don't have access to a PC right now

clang-tidy randomly fails, it's a known problem

[Pedro-Roque]

@beniaminopozzan @dakejahl shall we merge this one before we add the second option?