[partition] Goal of this branch: configurable default action

src/modules/partition/partition.conf

@@ -39,6 +39,16 @@ userSwapChoices:
     # - reuse     # Re-use existing swap, but don't create any (unsupported right now)
     # - file      # To swap file instead of partition (unsupported right now)
 
+# By default, when the user arrives at the partitioning page, no action
+# is selected (out of erase, reuse, ...). You can explicitly set None
+# here to select no action on arrival, **or** pick one of these
+# actions and that will be selected if it is available. If it isn't
+# available on arrival, no action will be selected.
+#   - erase
+#   - replace
+#   - alongside
+userDefaultAction: None
+
 # LEGACY SETTINGS (these will generate a warning)
 # ensureSuspendToDisk:    true
 # neverCreateSwap:        false