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.

tests.py

@@ -415,7 +415,7 @@ def test_create_log_file_names():
         mpsd_release=mpsd_release,
         date=date,
         action=action,
-        toolchain=toolchain,
+        package_set=toolchain,
     )
     assert (
         build_log_file_name
@@ -437,7 +437,7 @@ def test_create_log_file_names():
         mpsd_release=mpsd_release,
         date=date,
         action="status",
-        toolchain=toolchain,
+        package_set=toolchain,
     )
     assert build_log_file_name is None