Swift: add some ParamDecl methods

Author: rdmarsh2

swift/ql/lib/codeql/swift/elements/decl/ParamDecl.qll

@@ -1,4 +1,16 @@
-// generated by codegen/codegen.py, remove this comment if you wish to edit this file
 private import codeql.swift.generated.decl.ParamDecl
+private import codeql.swift.elements.decl.AbstractFunctionDecl
 
-class ParamDecl extends ParamDeclBase { }
+class ParamDecl extends ParamDeclBase { 
+  /** Gets the function which declares this parameter. */
+  AbstractFunctionDecl getDeclaringFunction() {
+    result.getAParam() = this
+  }
+
+  /** Gets the index of this parameter in its declaring function's parameter list. */
+  int getIndex() {
+    exists(AbstractFunctionDecl func |
+      func.getParam(result) = this
+    )
+  }
+}