Toolchain becomes package set part2

This is mostly a search and replace exercise (and thus probably correct). (Individual commits deal with kind-of single functions, and their associated tests.)

More complicated changes I have tried to move into separate merge requests.

mpsd-software.py

@@ -1003,7 +1003,11 @@ def environment_status(mpsd_release: str, root_dir: Union[str, Path]) -> dict:
     -------
     toolchain_map : dict
         A dictionary containing available microarchitectures as keys and
-        a list of available toolchains as values for each microarchitecture.
+        a list of available package_sets as values for each microarchitecture.
+
+        Note: only toolchains can be reported at the moment (i.e. package_sets
+        such as global and global_generic are missing, even if installed).
+
     """
     msg = f"Showing status of release {mpsd_release} in {root_dir}"
     logging.info(msg)