Merge series from Peter Ujfalusi <peter.ujfalusi@linux.intel.com>:

In IPC4 all DSP loadable executable is a 'library' containing modules. The main
or basefw is also a library which contains multiple modules.
IPC4 allows to use loadable libraries to extend the functionality of the booted
basefw.

This series adds support for loading external libraries in case they are needed
by the loaded topology file.

The libraries must be placed to a specific firmware directory (fw_lib_prefix),
which is:
intel/avs-lib|sof-ipc4-lib/ followed by the platform name and in case of
community key use a 'community' directory.

For example for upx-i11 (community key): intel/avs-lib/tgl/community is the
default path.

The name of the library should be the UUID of the module it contains since the
library loading is going to look for the file as <module_UUID>.bin
In case there is a need to bundle multiple modules into single library, symlinks
can be used to point to the file:

module_boundle.bin
<UUID1>.bin -> module_boundle.bin
<UUID2>.bin -> module_boundle.bin
<UUID3>.bin -> module_boundle.bin

But note that in this case all modules will be loaded to the DSP since only the
whole library can be loaded, not individual modules.