Fixed equals and hashCode

1. Used Android Studio to auto generate the equals
   and hashCode method.
2. e-order the field to match the database column order.
3. Better readability for toString().

Bug: 239607619
Test: atest SubscriptionDatabaseManagerTest
Merged-In: Ibc80d41f3019a4ebb012358f3369d69222925214
Change-Id: Ibc80d41f3019a4ebb012358f3369d69222925214