CacheKey collisions with multiple entity types using same ID

[ahardin]

Describe the bug If you have 2 entities (e.g. Order and Product) that have the same ID (e.g. 5), AppSync will confuse cached instances of those entities.

To Reproduce Steps to reproduce the behavior:

1. Create a schema with Order and Product entities as well as list/get queries for each.
2. In your database (or just hardcoded in a Lambda), create an Order record and a Product record, each with an ID of 5.
3. Use the Android AppSync client to retrieve those Orders and Products.
4. Observe the selectRecordForKey function in SqlNormalizedCache. It will simply query the SQlite database for a key of "5" rather than "Order:5" or "Product:5".

This causes a host of downstream issues for the user, but this is the most direct way to observe it.

Expected behavior The cache database should be queried with a key prepended with the entity type, as the documentation states here: ~~https://aws-amplify.github.io/docs/android/api#client-architecture~~ mysteriously moved to -> https://aws-amplify.github.io/docs/sdk/android/api#client-architecture

Environment(please complete the following information):

• AppSync SDK Version: 2.10.0

Failed workaround I tried simply implementing my own CacheKeyResolver to specify a custom CacheKey, but that led to separate strange behavior in which the entities cached by calling a list query (e.g. getOrders) were not found/used by a ByID query (e.g. getOrder(id)). That might merit an issue of its own, but let's see what happens here.