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

@@ -89,15 +89,15 @@ def create_log_file_names(
     microarch: str,
     action: str,
     date: str = call_date_iso,
-    toolchain: str = None,
+    package_set: str = None,
 ) -> Union[str, None]:
     """Create log file names.
 
     This function creates the log file names for either the installer or
     the build log files.
 
-    If a toolchain is given, then the build log file name is created.
-    if no toolchain is given, then the installer log file name is created.
+    If a package_set is given, then the build log file name is created.
+    if no package_set is given, then the installer log file name is created.
     The installer log file hosts the logs of the installer script, while
     the build log file hosts the logs of the build process as generated by the
     spack_setup.sh script.
@@ -113,8 +113,8 @@ def create_log_file_names(
     action : str
         action performed (install,remove,reinstall,prepare,status)
         only install and remove are valid for build log file.
-    toolchain : str
-        toolchain name (only for build log file)
+    package_set : str
+        package_set name (only for build log file)
 
     Returns
     -------
@@ -125,16 +125,16 @@ def create_log_file_names(
         If the action is not one that changes the files on disk ( info only actions)
         then None is returned.
     """
-    if toolchain:
-        # if toolchain is given, then  we build the build_log_file_name
+    if package_set:
+        # if package_set is given, then  we build the build_log_file_name
         if action in ["install", "remove"]:
             log_file_name = (
-                f"{mpsd_release}_{microarch}_{date}_BUILD_{toolchain}_{action}.log"
+                f"{mpsd_release}_{microarch}_{date}_BUILD_{package_set}_{action}.log"
             )
         else:
             return None
     else:
-        # if toolchain is not given, then we build the installer_log_file_name
+        # if package_set is not given, then we build the installer_log_file_name
         log_file_name = f"{mpsd_release}_{microarch}_{date}_APEX_{action}.log"
 
     return log_file_name
@@ -266,7 +266,7 @@ def set_up_logging(loglevel="warning", file_path=None):
 
        Typical and intended use:
 
-       print_log.info("Available toolchains are ...")
+       print_log.info("Available package_sets are ...")
 
        The major difference from the normal print command is that the output
        will be send to the stdout (as for print) AND the file with name