asp: refactor low level API to permit the injection of configuration

This allows writing extension commands that can benchmark
different configurations in clingo, or try different
configurations for a single test.

lib/spack/docs/conf.py

@@ -200,6 +200,7 @@ def setup(sphinx):
     ("py:class", "_io.BufferedReader"),
     ("py:class", "unittest.case.TestCase"),
     ("py:class", "_frozen_importlib_external.SourceFileLoader"),
+    ("py:class", "clingo.Control"),
     # Spack classes that are private and we don't want to expose
     ("py:class", "spack.provider_index._IndexBase"),
     ("py:class", "spack.repo._PrependFileLoader"),