Fix flag app being empty.

Kotlin evaluates `object` declarations lazily.
We have to access `Flags` before it will populate
the list, and we were asking for the list during
construction of our dagger graph.

Bug: 257302229
Test: manual
Change-Id: Iadfbbbc50ee2fb09260f5d119898fb50b3cc90f9

packages/SystemUI/src-debug/com/android/systemui/flags/FlagsFactory.kt

@@ -22,7 +22,11 @@ object FlagsFactory {
     private val flagMap = mutableMapOf<String, Flag<*>>()
 
     val knownFlags: Map<String, Flag<*>>
-        get() = flagMap
+        get() {
+            // We need to access Flags in order to initialize our map.
+            assert(flagMap.contains(Flags.TEAMFOOD.name)) { "Where is teamfood?" }
+            return flagMap
+        }
 
     fun unreleasedFlag(
         id: Int,

packages/SystemUI/src-release/com/android/systemui/flags/FlagsFactory.kt

@@ -22,7 +22,11 @@ object FlagsFactory {
     private val flagMap = mutableMapOf<String, Flag<*>>()
 
     val knownFlags: Map<String, Flag<*>>
-        get() = flagMap
+        get() {
+            // We need to access Flags in order to initialize our map.
+            assert(flagMap.contains(Flags.TEAMFOOD.name)) { "Where is teamfood?" }
+            return flagMap
+        }
 
     fun unreleasedFlag(
         id: Int,