Swift: add getSequence back to ForEachStmt

Author: rdmarsh2

swift/ql/lib/codeql/swift/elements/stmt/ForEachStmt.qll

@@ -6,4 +6,12 @@ class ForEachStmt extends Generated::ForEachStmt {
     then result = "for ... in ... where ... { ... }"
     else result = "for ... in ... { ... }"
   }
+
+  /*
+   * Gets the sequence of this for each statement.
+   */
+
+  final Expr getSequence() {
+    result = this.getIteratorVar().getInit(0)
+  }
 }