Launch-lines will be pasted into a shell, and `gst_value_serialize()`
yields strings that will likely be interpreted by the shell. For
example:
`gst-launch-1.0 ... ! osxaudiosink unique-id="AppleUSBAudioEngine:BEHRINGER:UMC202HD\ 192k:12345678:1\,2"`
The shell will remove the double-quotes `"` but keep the `\ ` which
means the output of `gst_value_deserialize()` will not be the original
string, and the launch line will not work.
So let's use `gst_value_serialize()` only if the string is non-ASCII,
and if it's ASCII and needs quoting, we do some shell quoting.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/9466>
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