Add a pixi toml url to the build parameter arguments (ported from #839)

[knmcguire]

See the description of #839

Ported to be a branch in ROS/ci so that we could more easily deploy it on a test ci job to test it out according to @claraberendsen

[knmcguire]

The idea is that we will try to deploy this particular branch on one of the test_ci jobs just to try it out since there is no CI to this PR. So we can wait with merging this PR after we have looked and settled that

[cottsay]

@knmcguire, I rebased this to make it easier to deploy to the test_* jobs, FYI.

[cottsay]

Deployed here: https://ci.ros2.org/job/test_ci_windows/

[knmcguire]

Thanks! And good we tested it out here because it indeed fails! I will look into it 😄

[knmcguire]

Still testing things out in the test ci! the latest github outages delayed that a bit, so as soon as I confirm this working I'll convert it back to 'ready for review'

[knmcguire]

Test with empty CI_PIXI_TOML_URL:

Test with msvc 2022 and with an alternative pixi.toml file (for the opencv fix) :

I don't think it is setting the pixi_toml_url correctly... so still some work to do here

[claraberendsen]

@knmcguire I think what is missing is to correctly set the new variable as DOCKER_BUILD_ARGS

See the reference

ci/job_templates/ci_job.xml.em

Lines 175 to 177 in db24a7c

	if [ -n "${CI_ROS_DISTRO+x}" ]; then
	export DOCKER_BUILD_ARGS="${DOCKER_BUILD_ARGS} --build-arg ROS_DISTRO=${CI_ROS_DISTRO}"
	fi