refactor(flatten-threads): migrate to the new DI architecture

Bug: twpowertools:176
Change-Id: I7a24fb504ce53697112f11128d2d5249a5a7c7e7
diff --git a/src/entryPoints/communityConsole/contentScripts/start.ts b/src/entryPoints/communityConsole/contentScripts/start.ts
index 72302ff..21ef427 100644
--- a/src/entryPoints/communityConsole/contentScripts/start.ts
+++ b/src/entryPoints/communityConsole/contentScripts/start.ts
@@ -24,6 +24,8 @@
 import ApplyStartupDataModificationsOnStartScript from '../../../presentation/standaloneScripts/startupDataStorage/applyStartupDataModificationsOnStart.script';
 import XHRInterceptorScript from '../../../presentation/standaloneScripts/xhrInterceptor/xhrInterceptor.script';
 import ThreadPageDesignWarningSetUpScript from '../../../features/threadPageDesignWarning/presentation/scripts/setUp.script';
+import FlattenThreadsSetUpReplyActionHandlerScript from '../../../features/flattenThreads/presentation/scripts/setUpReplyActionHandler.script';
+import FlattenThreadsReplyActionHandler from '../../../features/flattenThreads/core/replyActionHandler';
 
 const scriptRunner = createScriptRunner();
 scriptRunner.run();
@@ -53,10 +55,11 @@
         new CCDarkThemeInjectAutoDarkTheme(),
         new CCDarkThemeInjectForcedDarkTheme(),
         new CCExtraInfoSetUpScript(extraInfo),
-        new InteropThreadPageSetupScript(),
-        new ThreadPageDesignWarningSetUpScript(
-          threadPageDesignWarning,
+        new FlattenThreadsSetUpReplyActionHandlerScript(
+          new FlattenThreadsReplyActionHandler(optionsProvider),
         ),
+        new InteropThreadPageSetupScript(),
+        new ThreadPageDesignWarningSetUpScript(threadPageDesignWarning),
         new LoadDraftsSetupScript(optionsProvider, startupDataStorage),
         new WorkflowsImportSetUpScript(workflowsImport),