Fix for Issue 845 - InMemory EnsureCreated() should return true for the
first call to create a database and false thereafter.
Error with the Error Page, "How Meta" - Enable error page for non-collection queries
Exceptions from queries that return a single entity or a scalar value were not triggering the error page as they do not go through MoveNext in our wrapping Enumerable. Adding logging to handle these cases (and applicable unit tests).
Adding information to the model about whether the bool metadata properties have been set to default values explicitly.
Use me! Use me!

Update stack to use new provider-specific APIs

And remove older APIs. This updates query, Migrations, and update pipeline to use the new annotations through the new APIs and to use provider-specific annotations, rather than just relational annotations. File issues for:
* SQLite provider-specific APIs and their use
* Clustered is SQL Server specific except in Migrations
* Use of SQL Server specific values for column names in query
* Cascade deletes are not supported in the stack
Query: Relational: Enabled Include for async queries.

- Added async include tests to SQLServer, SQLite
- Fixed some async call sites that were not flowing a cancellation token.
- Some further de-nesting of query component classes.
Query: Relational: Async: Make All/Any/Count non-blocking.