python: Start modelling using MaD

- empty models for now
- `summaryModel` of `codeql/python-all` will be added to shortly.

python/ql/lib/ext/StdLib.model.yml

@@ -0,0 +1,30 @@
+extensions:
+  - addsTo:
+      pack: codeql/python-all
+      extensible: sourceModel
+    data: []
+
+  - addsTo:
+      pack: codeql/python-all
+      extensible: sinkModel
+    data: []
+
+  - addsTo:
+      pack: codeql/python-all
+      extensible: summaryModel
+    data: []
+
+  - addsTo:
+      pack: codeql/python-all
+      extensible: neutralModel
+    data: []
+
+  - addsTo:
+      pack: codeql/python-all
+      extensible: typeModel
+    data: []
+
+  - addsTo:
+      pack: codeql/python-all
+      extensible: typeVariableModel
+    data: []

python/ql/lib/qlpack.yml

@@ -15,4 +15,6 @@ dependencies:
   codeql/yaml: ${workspace}
 dataExtensions:
   - semmle/python/frameworks/**/*.model.yml
+  - ext/*.model.yml
+  - ext/generated/*.model.yml
 warnOnImplicitThis: true