Per upstream this function is not supposed to be called by users of
PipeWire, and will crash when called twice. Instead only call it on
recent versions of PipeWire where it is safe to call.
This also removes the nearly empty pipewire-common files.
Status output related to OBS configuration is prefixed with the string
"OBS" and added padding for enabled and disabled features. This padding
was not aligned between platforms.
By moving the padding and prefix decoration into its own function,
both elements are controlled in a single place. CMake scripts were
changed to use this new function `obs_status` instead of using CMake's
`message` function directly.
