Fix backwards compatibility for module naming (#11236)

f242f5f8 changed the format strings but maintained backwards
compatibility in all cases except one: The list of valid tokens for
the module naming schemes was not updated properly to contain both
the new and old styles for compilers and package names.

This PR re-adds the old tokens into the list of valid tokens.

lib/spack/spack/modules/common.py

@@ -65,6 +65,10 @@
     'compiler.name',
     'compiler.version',
     'architecture'
+    # tokens from old-style format strings
+    'package',
+    'compilername',
+    'compilerver',
 )