Hacks for Testing latest `libsdformat` stuff

Deps

For Ubuntu Bionic (may need ROS repos...)

sudo apt install \
    libtinyxml2-dev python3-vcstool python3-colcon-common-extensions

Then update repositories (and record the exact versions afterwards):

(
    set -eux
    vcs import ./ < ./meta/vcs.repo
    vcs export --exact ./ > ./meta/vcs-exact.repo
)

First, test without Bazel overhead:

colcon build
colcon test
# Or just go the build package, and run `make test` / `ctest`.