Implemented the CardContentLoader

- Implemented the CardContentLoader
- Refactored the CardLoader and increased the code readable
- Added try-with-resource
- Removed all custom card codes
- Modified ContextualCardManager to add CardContentLoaderCallbacks

Bug: 112521307
Test: robotest
Change-Id: Ieb9cdeaacdfb8fdae9747c60395206d15af034c1

src/com/android/settings/homepage/CardDatabaseHelper.java

@@ -17,6 +17,7 @@
 package com.android.settings.homepage;
 
 import android.content.Context;
+import android.database.Cursor;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteOpenHelper;
 import android.util.Log;
@@ -190,4 +191,12 @@ public class CardDatabaseHelper extends SQLiteOpenHelper {
         }
         return sCardDatabaseHelper;
     }
+
+    Cursor getAllContextualCards() {
+        final SQLiteDatabase db = this.getReadableDatabase();
+        Cursor cursor = db.query(CARD_TABLE, null /* columns */, null /* selection */,
+                null /* selectionArgs */, null /* groupBy */, null /* having */,
+                null /* orderBy */);
+        return cursor;
+    }
 }