Added Debian bullseye support for the installer

[marnunez]

Brief summary of changes

Changed to use ID of OS instead of NAME
Only use VERSION_ID if ID == "ubuntu"

Testing I've completed

Built on my own Debian bullseye/sid

[aymanhab]

Thanks for submitting this @marnunez, quick feedback:

1. whitespace/tab changes makes it hard to see the actual diffs, can you fix that?
2. In our current work-from-home environment, and moving forward it is hard to access/test linux installers, so it would be good to leverage/test the artifacts produced by github actions on actual machines running linux.

[marnunez]

1. Sorry about the autoformatting, my bad.
2. I see what you mean, how would you suggest to approach this? There's no ready github actions build for a Debian environment, but something more fancy using self-hosted runners might be done if needed. As for now, I did build and install this PR with the Debian machine I'm using, for what it's worth...

[aymanhab]

@marnunez If you fix the formatting, and @halleysfifthinc approves the change (to make sure it doesn't break his changes, I don't have access to either platforms) that would be great. Also please include in this PR, adding your name to the list of contributors in the contributing.md file. Thank you

[halleysfifthinc]

The added whitespace will need to be removed or else it will show up in the printf statements and mess with the output indenting.

[halleysfifthinc]

Suggested change

	Comment=OpenSim is an open source software for neuromusculoskeletal modeling, simulation \
	and analysis.
	Comment=Neuromusculoskeletal modeling, simulation, and analysis.

We had changed this in the standalone desktop file but I noticed that I had forgot to make that change here as well.

[halleysfifthinc]

Is there a reason (ie in terms of an expectation of a non-exact match) for using the =~ comparison for matching "bullseye"? I'm not familiar with Debian

[halleysfifthinc]

My bash skills aren't the greatest (and I wasn't able to figure it out with some quick googling); can you explain what the +x is doing? Also, if you're negating the -z option, wouldn't using -n or even just [ "$VERSION_ID+x}" ] be more concise/readable?

[halleysfifthinc]

This variable appears to be unused now and can be removed?

[halleysfifthinc]

Regarding the Actions CI artifacts, I believe what @aymanhab is suggesting is to check that the installer produced by CI works by test installing it on your machine.

[artgodwin]

I have run the build script under Debian bullseye and found 1 issue :
it needs default-jdk in the preinstalls.

However, the installation crashes very easily including on the examples. Not sure if this is a problem with any older libs included in debian