Add missing PreResolve plugin hook

Source/DafnyCore/Plugins/Rewriter.cs

@@ -32,6 +32,14 @@ public virtual void PostResolve(Program program) {
       Contract.Requires(program != null);
     }
 
+    /// <summary>
+    /// Override this method to perform changes to the AST of a module before resolution.
+    /// You can also report warnings and errors using reporter.Error
+    /// </summary>
+    /// <param name="module">The module before resolution</param>
+    public virtual void PreResolve(ModuleDefinition module) {
+    }
+
     /// <summary>
     /// Override this method to obtain the resolved module before the translation pipeline occurs
     /// after the individual PostResolve on every module

Source/DafnyCore/Rewriters/PluginRewriter.cs

@@ -15,6 +15,10 @@ internal override void PostResolve(Program program) {
     internalRewriter.PostResolve(program);
   }
 
+  internal override void PreResolve(ModuleDefinition module) {
+    internalRewriter.PreResolve(module);
+  }
+
   internal override void PreVerify(ModuleDefinition module) {
     internalRewriter.PreVerify(module);
   }