chore(explore): Add feature flag to enable explore rpc (#82585)

Getting ready to enable RPC by default in explore and it'll be enabled
behind this feature flag.

src/sentry/features/temporary.py

@@ -527,6 +527,8 @@ def register_temporary_features(manager: FeatureManager):
     manager.add("organizations:visibility-explore-view", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
     # Enable the dataset toggle on the new explore page
     manager.add("organizations:visibility-explore-dataset", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
+    # Enable RPC on the new explore page
+    manager.add("organizations:visibility-explore-rpc", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
     # Enable minimap in the widget viewer modal in dashboards
     manager.add("organizations:widget-viewer-modal-minimap", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
     # Enabled unresolved issue webhook for organization