alsa: add volume limits

Add 3 levels of volume limits.

1. Add api.acp.min-volume and api.acp.max-valume on the ACP devices that
   is applied to all noded from this device
2. Add api.acp.device.<node-name>.min-volume and
   api.acp.device.<node-name>.max-volume that is applied to all nodes
   from the device with the given node-name.
3. Add api.acp.port.<port-name>.min-volume and
   api.acp.port.<port-name>.max-volume that is applied to all ports
   from the device with the given port-name.

The volume settings on an ALSA nodes can either go through the device on
the Routes (ports) to control the hardware mixer volumes and then the
remainder is performed on the nodes in software by the channel mixer.

We need to set the limits on the channel mixer when the hardware mixer
does not have routes.

This is not an easy way to set the volume limits but it provides a
static configuration option to enforce the limits. An easier
configuration option will also make it easier to change/bypass the
limits, which these options can guard against.

See #5266, #4323, #1517

spa/plugins/alsa/acp/device-port.h

@@ -76,6 +76,7 @@ struct pa_device_port {
 
 	pa_direction_t direction;
 	int64_t latency_offset;
+	float volume_range[2];
 
 	pa_proplist *proplist;
 	pa_hashmap *profiles;