Add escape function.

Author: gagliardetto

ql/src/semmle/go/frameworks/stdlib/Html.qll

@@ -6,6 +6,14 @@ import go
 
 /** Provides models of commonly used functions in the `html` package. */
 module Html {
+  private class Escape extends EscapeFunction::Range {
+    string kind;
+
+    Escape() { hasQualifiedName("html", "EscapeString") and kind = "html" }
+
+    override string kind() { result = kind }
+  }
+
   private class FunctionModels extends TaintTracking::FunctionModel {
     FunctionInput inp;
     FunctionOutput outp;