fix: Add missing getModuleEvaluationSideEffectsState

It looks like webpack can expect this method to be defined in certain
cases.

Related to storybookjs/storybook#15221.

Author: bebraw

src/dependency.ts

@@ -18,6 +18,10 @@ class DocGenDependency extends NullDependency {
     this.codeBlock = codeBlock;
   }
 
+  getModuleEvaluationSideEffectsState(): boolean {
+    return false;
+  }
+
   updateHash: webpack.dependencies.NullDependency["updateHash"] = (hash) => {
     hash.update(this.codeBlock);
   };