Packaging: Rafactor Python core libraries

Extract the external facing `qll` files into the codeql/python-all
query pack.

python/ql/lib/python.qll

@@ -0,0 +1,43 @@
+import Customizations
+import semmle.python.Files
+import semmle.python.Operations
+import semmle.python.Variables
+import semmle.python.AstGenerated
+import semmle.python.AstExtended
+import semmle.python.Function
+import semmle.python.Module
+import semmle.python.Class
+import semmle.python.Import
+import semmle.python.Stmts
+import semmle.python.Exprs
+import semmle.python.Keywords
+import semmle.python.Comprehensions
+import semmle.python.Flow
+import semmle.python.Metrics
+import semmle.python.Constants
+import semmle.python.Scope
+import semmle.python.Comment
+import semmle.python.GuardedControlFlow
+import semmle.python.types.ImportTime
+import semmle.python.types.Object
+import semmle.python.types.ClassObject
+import semmle.python.types.FunctionObject
+import semmle.python.types.ModuleObject
+import semmle.python.types.Version
+import semmle.python.types.Descriptors
+import semmle.python.protocols
+import semmle.python.SSA
+import semmle.python.SelfAttribute
+import semmle.python.types.Properties
+import semmle.python.xml.XML
+import semmle.python.essa.Essa
+import semmle.python.pointsto.Base
+import semmle.python.pointsto.Context
+import semmle.python.pointsto.CallGraph
+import semmle.python.objects.ObjectAPI
+import semmle.python.Unit
+import site
+// Removing this import perturbs the compilation process enough that the points-to analysis gets
+// compiled -- and cached -- differently depending on whether the data flow library is imported. By
+// importing it privately here, we ensure that the points-to analysis is compiled the same way.
+private import semmle.python.dataflow.new.DataFlow