Refactor WifiSlice to CustomSliceManager

Modify the WifiSliceCode to follow the pattern for
Slices that do not match existing UI components.

Test: robotests
Bug: 80263568
Change-Id: Id69e019608777282f4b64ff945e8c30c97aaf577

tests/robotests/src/com/android/settings/slices/SpecialCaseSliceManagerTest.java

@@ -112,10 +112,14 @@ public class SpecialCaseSliceManagerTest {
 
         static boolean backingData = false;
 
-        public FakeSliceable(Context context) {}
+        final Context mContext;
+
+        public FakeSliceable(Context context) {
+            mContext = context;
+        }
 
         @Override
-        public Slice getSlice(Context context) {
+        public Slice getSlice() {
             return SLICE;
         }
 
@@ -133,5 +137,10 @@ public class SpecialCaseSliceManagerTest {
         public IntentFilter getIntentFilter() {
             return new IntentFilter();
         }
+
+        @Override
+        public Intent getIntent() {
+            return null;
+        }
     }
 }