Previously, there were two problems with DevTools’ DataSource
auto-configuration:

1. It did not tolerate a context with multiple DataSources
2. It would attempt to shut down a DataSource that had not been created
   by DataSourceAutoConfiguration and, therefore, where we could not be
   sure of its configuration.

This commit updates DevToolsDataSourceAutoConfiguration so that it backs
off unless the context contains DataSourceProperties and a single
DataSource created by DataSourceAutoConfiguration. This ensures that it
can safely use DataSourceProperties to get the DataSource’s
driver class name and accurately determine if it’s an in-memory or
external database. Shutdown is only called for an in-memory database.

Closes gh-5540