feat: add validator run event to allow plugins to perform custom validation (#2184)

* feat: add validator run event to allow plugins to perform custom validation

Author: RebeccaStevens

src/lib/application-events.ts

@@ -1,3 +1,4 @@
 export const ApplicationEvents = {
     BOOTSTRAP_END: "bootstrapEnd",
+    VALIDATE_PROJECT: "validateProject",
 };

src/lib/application.ts

@@ -107,6 +107,12 @@ export class Application extends ChildableComponent<
      */
     static readonly EVENT_BOOTSTRAP_END = ApplicationEvents.BOOTSTRAP_END;
 
+    /**
+     * Emitted when validation is being run.
+     * The listener will be given an instance of {@link ProjectReflection}.
+     */
+    static readonly EVENT_VALIDATE_PROJECT = ApplicationEvents.VALIDATE_PROJECT;
+
     /**
      * Create a new TypeDoc application instance.
      */
@@ -431,6 +437,8 @@ export class Application extends ChildableComponent<
             validateLinks(project, this.logger);
         }
 
+        this.trigger(Application.EVENT_VALIDATE_PROJECT, project);
+
         this.logger.verbose(`Validation took ${Date.now() - start}ms`);
     }