Add default strategy type to strategy hook

- Fixes the missing sidebar while loading the strategy types
  Trello:
  https://trello.com/c/WJk8bI8l/490-feature-strategies-loading-state

frontend/src/hooks/api/getters/useStrategies/useStrategies.ts

@@ -6,13 +6,29 @@ import handleErrorResponses from '../httpErrorResponseHandler';
 
 export const STRATEGIES_CACHE_KEY = 'api/admin/strategies';
 
+const flexibleRolloutStrategy: IStrategy = {
+    deprecated: false,
+    name: 'flexibleRollout',
+    displayName: 'Gradual rollout',
+    editable: false,
+    description: 'Roll out to a percentage of your userbase, and ensure that the experience is the same for the user on each visit.',
+    parameters: [{
+        name: 'rollout', type: 'percentage', description: '', required: false
+    }, {
+        name: 'stickiness',
+        type: 'string',
+        description: 'Used to defined stickiness',
+        required: true
+    }, { name: 'groupId', type: 'string', description: '', required: true }]
+};
+
 const useStrategies = () => {
     const fetcher = () => {
         const path = formatApiPath(`api/admin/strategies`);
 
         return fetch(path, {
             method: 'GET',
-            credentials: 'include',
+            credentials: 'include'
         }).then(handleErrorResponses('Strategies')).then(res => res.json());
     };
 
@@ -31,10 +47,10 @@ const useStrategies = () => {
     }, [data, error]);
 
     return {
-        strategies: data?.strategies || [],
+        strategies: data?.strategies || [flexibleRolloutStrategy],
         error,
         loading,
-        refetch,
+        refetch
     };
 };