Python: Move some non-points-to methods out of points-to

These methods were in `pointsto.Base` but did not actually interact with
the points-to machinery directly, so they were easy to move out.

Author: tausbn

python/ql/lib/semmle/python/essa/Definitions.qll

@@ -276,6 +276,17 @@ class ModuleVariable extends SsaSourceVariable instanceof GlobalVariable {
   override CallNode redefinedAtCallSite() { none() }
 }
 
+/** Holds if `f` is an import of the form `from .[...] import ...` and the enclosing scope is an __init__ module */
+private predicate import_from_dot_in_init(ImportExprNode f) {
+  f.getScope() = any(Module m).getInitModule() and
+  (
+    f.getNode().getLevel() = 1 and
+    not exists(f.getNode().getName())
+    or
+    f.getNode().getImportedModuleName() = f.getEnclosingModule().getPackage().getName()
+  )
+}
+
 class NonEscapingGlobalVariable extends ModuleVariable {
   NonEscapingGlobalVariable() {
     this instanceof GlobalVariable and

python/ql/lib/semmle/python/essa/SsaDefinitions.qll

@@ -7,6 +7,13 @@ import python
 private import semmle.python.internal.CachedStages
 private import LegacyPointsTo
 
+/** Hold if `expr` is a test (a branch) and `use` is within that test */
+predicate test_contains(ControlFlowNode expr, ControlFlowNode use) {
+  expr.getNode() instanceof Expr and
+  expr.isBranch() and
+  expr.getAChild*() = use
+}
+
 cached
 module SsaSource {
   /** Holds if `v` is used as the receiver in a method call. */