[REFACTOR] DynamicPartitionControl: combine DAP feature flag APIs

Combine IsDynamicPartitionsEnabled/Retrofit into one API that
returns a FeatureFlag struct instead.

This allows us to add new feature flags more easily.

Test: unittest
Change-Id: I32f0f0c4d5c636d2eac3bf99d6f92fcc6b71c7a9
diff --git a/boot_control_android_unittest.cc b/boot_control_android_unittest.cc
index dfcb6fb..3e0320d 100644
--- a/boot_control_android_unittest.cc
+++ b/boot_control_android_unittest.cc
@@ -274,10 +274,8 @@
           return Void();
         }));
 
-    ON_CALL(dynamicControl(), IsDynamicPartitionsEnabled())
-        .WillByDefault(Return(true));
-    ON_CALL(dynamicControl(), IsDynamicPartitionsRetrofit())
-        .WillByDefault(Return(false));
+    ON_CALL(dynamicControl(), GetDynamicPartitionsFeatureFlag())
+        .WillByDefault(Return(FeatureFlag(FeatureFlag::Value::LAUNCH)));
     ON_CALL(dynamicControl(), DeviceExists(_)).WillByDefault(Return(true));
     ON_CALL(dynamicControl(), GetDeviceDir(_))
         .WillByDefault(Invoke([](auto path) {