FeatureFlags: define features outside settings.Cfg (take 3) (#44443)

pkg/services/featuremgmt/testdata/features.yaml

@@ -0,0 +1,33 @@
+include:
+ - included.yaml # not yet supported
+
+vars: 
+  stack: something
+  level: free
+  valA: value from features.yaml
+
+flags: 
+  - name: feature1
+    description: feature1
+    expression: "false"
+
+  - name: feature3
+    description: feature3
+    expression: "true"
+
+  - name: feature3
+    description: feature3
+    expression: env.level == 'free'
+
+  - name: displaySwedishTheme
+    description: enable swedish background theme
+    expression: |
+      // restrict to users allowing swedish language
+      req.locale.contains("sv")
+  - name: displayFrenchFlag
+    description: sho background theme
+    expression: |
+      // only admins
+      user.id == 1
+      // show to users allowing french language
+      && req.locale.contains("fr")

pkg/services/featuremgmt/testdata/included.yaml

@@ -0,0 +1,13 @@
+include:
+ - features.yaml # make sure we avoid recusion!
+
+# variables that can be used in expressions
+vars:
+  stack: something
+  deep: 1
+  valA: value from included.yaml
+
+flags: 
+  - name: featureFromIncludedFile
+    description: an inlcuded file
+    expression: invalid expression string here