Fix/snap rosbag

[Guillaumebeuzeboc]

This PR slightly alters the snap, resulting in the following user experience,
Install the snap,

sudo snap install plutjuggler

Launch the snap with ROS support,

plotjuggler

This is also achieved hitting the desktop launcher. It is on par with the behaviour of the current ‘stable’ snap. So far, no disruption for users.

The actual change is the introduction of two new commands,

plotjuggler.ros
plotjuggler.ros2

Which respectively (explicitly) launch PJ with ROS or ROS 2 support.
Finally, users are able to change the behaviour of the ‘plotjuggler’ command as follows,

sudo snap set plotjuggler ros-plugin-version=2

So that the command now launches PJ with ROS 2 support instead of ROS.

This change is the result of fixing the issue with loading rosbags.

Being able to load rosbag brought up two main problems:

• Due to libraries that have the same name (libclass_loader.so) both ROS/ROS 2 plugins cannot be loaded at the same time
• ROS 2 bag metadata.yaml are referring to the .db3 file relatively. In snaps GUI with Qt, files loaded with QFileDialog are fuse-mounted to /run/user/<uid>/doc/<hash>/ in order to give your snapped application access to it (from the xdg-desktop-portals). The .db3 file is then searched within /run/user/<uid>/doc/<hash>/ which only contains the metadata.yaml.

This PR also includes:

• GitHub workflow action is now checking out the full history of the repository since we need the latest tag for the snap versioning.
• ZMQ build was removed since now ZMQ can be found from the deb package

This PR does not disrupt any existing install while bringing ROS 2 support along with an explicit command.

Feel free to ask any questions regarding the snap or its usage.

[facontidavide]

since I don't understand any of this... I will just merge it. Thanks!

[facontidavide]

I just released the tag 3.5.2, but it looks like it is still in devmode:

[Guillaumebeuzeboc]

The CI released the snap under the "stable" grade : https://github.com/facontidavide/PlotJuggler/runs/7689122227?check_suite_focus=true#step:3:3337

And the was published to the candidate channel: https://github.com/facontidavide/PlotJuggler/runs/7689877367?check_suite_focus=true#step:3:201

So everything went well on the CI side.

The plotjuggler snapstore page doesn't show this candidate release, and this is not normal.
I don't why yet. I will ask internally and come back to you once I know more