When api.alsa.split-enable=true for ACP device, instruct UCM to not
use alsa-lib plugins for SplitPCM devices.
Grab the information from UCM for the intended channel remapping, and
add the splitting information to the nodes emitted.
Session manager can then look at that, and load nodes to do the channel
splitting.
Don't use the api.alsa.soft-mixer option to disable the path selection
but make a new api.alsa.disable-mixer-path.
Disabling the path selection might leave cards unusable after suspend,
so a separate option is a better idea.
See #4311
Collect the list of object properties into a single place.
Group properties in the index based on the object type. Consider
"Monitor" as a separate object type, as it's generally configured
separately.
Add something about Port, Link, and Client properties. Just explain some
of these as they're fairly technical, so just link to API docs.
