feat(slack): feature flag for pre-GA slack block kit changes (#65164)

src/sentry/conf/server.py

@@ -1880,6 +1880,8 @@ SENTRY_FEATURES: dict[str, bool | None] = {
     "organizations:spike-protection-decay-heuristic": False,
     # Enable Slack messages using Block Kit
     "organizations:slack-block-kit": False,
+    # Improvements to Slack messages using Block Kit
+    "organizations:slack-block-kit-improvements": False,
     # Enable basic SSO functionality, providing configurable single sign on
     # using services like GitHub / Google. This is *not* the same as the signup
     # and login with Github / Azure DevOps that sentry.io provides.

src/sentry/features/__init__.py

@@ -254,6 +254,7 @@ default_manager.add("organizations:session-replay-weekly-email", OrganizationFea
 default_manager.add("organizations:set-grouping-config", OrganizationFeature, FeatureHandlerStrategy.INTERNAL)
 default_manager.add("organizations:settings-legal-tos-ui", OrganizationFeature, FeatureHandlerStrategy.REMOTE)
 default_manager.add("organizations:slack-block-kit", OrganizationFeature, FeatureHandlerStrategy.INTERNAL)
+default_manager.add("organizations:slack-block-kit-improvements", OrganizationFeature, FeatureHandlerStrategy.INTERNAL)
 default_manager.add("organizations:slack-overage-notifications", OrganizationFeature, FeatureHandlerStrategy.REMOTE)
 default_manager.add("organizations:source-maps-debugger-blue-thunder-edition", OrganizationFeature, FeatureHandlerStrategy.REMOTE)
 default_manager.add("organizations:sourcemaps-bundle-flat-file-indexing", OrganizationFeature, FeatureHandlerStrategy.REMOTE)