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

@@ -941,7 +941,7 @@ def install_environment(
         for toolchain in toolchains:
             # Set the install log file name from create_log_file_names
             build_log_file_name = create_log_file_names(
-                mpsd_release, microarch, "install", toolchain=toolchain
+                mpsd_release, microarch, "install", package_set=toolchain
             )
             build_log_folder = release_base_dir / "logs"
             build_log_path = build_log_folder / build_log_file_name