userspace: proxy: Introduce user worker to service IPC

The non-privileged modules code should be executed in separate thread
executed in userspace mode. This way the code and data owned by such
module will be isolated from other non-privileged modules in the system.

The implementation creates user work queue thread that will service all
IPC's for all such modules.

Signed-off-by: Adrian Warecki <adrian.warecki@intel.com>
Signed-off-by: Jaroslaw Stelter <Jaroslaw.Stelter@intel.com>

Author: jxstelter

src/audio/module_adapter/CMakeLists.txt

@@ -66,6 +66,7 @@ if(zephyr) ###  Zephyr ###
 
 	zephyr_library_sources_ifdef(CONFIG_SOF_USERSPACE_PROXY
 		library/userspace_proxy.c
+		library/userspace_proxy_user.c
 	)
 
 	zephyr_library_sources_ifdef(CONFIG_PASSTHROUGH_CODEC