sagemathgh-36910: System package quoting fixes

    
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The format of the `distros/*.txt` was underspecified. We now clarify
that there should be 1 package per line and no shell quoting.

We extend the system package scripts so that they apply shell quoting
when they print shell commands.
This fixes a failure seen in CI due to underquoting: https://github.com/
sagemath/sage/actions/runs/7202678226/job/19621287638#step:11:134

We also wrap the command lines that are displayed by `sage-spkg-info`
and formatted for the installation guide.
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URL: sagemath#36910
Reported by: Matthias Köppe
Reviewer(s): Dima Pasechnik, Matthias Köppe