Add missing unleash strategy required by some clients

ee/app/models/operations/feature_flag.rb

@@ -16,5 +16,11 @@ module Operations
     validates :description, allow_blank: true, length: 0..255
 
     scope :ordered, -> { order(:name) }
+
+    def strategies
+      [
+        { name: 'default' }
+      ]
+    end
   end
 end

ee/lib/ee/api/entities.rb

@@ -432,6 +432,7 @@ module EE
         expose :name
         expose :description, unless: ->(feature) { feature.description.nil? }
         expose :active, as: :enabled
+        expose :strategies
       end
 
       class UnleashFeatures < Grape::Entity

ee/spec/fixtures/api/schemas/unleash/unleash_feature.json

@@ -3,7 +3,8 @@
   "additionalProperties": false,
   "required": [
     "name",
-    "enabled"
+    "enabled",
+    "strategies"
   ],
   "properties": {
     "name": {
@@ -14,6 +15,13 @@
     },
     "description": {
       "type": "string"
+    },
+    "strategies": {
+      "items": {
+        "$ref": "unleash_strategy.json"
+      },
+      "minItems": 1,
+      "type": "array"
     }
   }
 }

ee/spec/fixtures/api/schemas/unleash/unleash_strategy.json

+{
+  "type": "object",
+  "additionalProperties": false,
+  "required": [
+    "name"
+  ],
+  "properties": {
+    "name": {
+      "type": "string"
+    }
+  }
+}