Add app.config transformations

[tsahi]

Is your feature request related to a problem? Please describe.
DAAB has some basic configurations to make before it can be used. The packages should add these configurations to the app/web.config file.

Describe the solution you'd like
When the Data or one of the database-specific packages is installed,

1. the ConfigurationSection should be added to the <configSections> element. If one is using the GenericDatabase, then s/he only needs the Data package.
2. The <dataConfiguration> should be added for a database-specific package
3. The Data.Oracle package should also add the Oracle configuration.

Describe alternatives you've considered

1. Document how to configure. This should be done in any case, in case the user wants to customize the default configuration.
2. The Patterns & Practices team once created an extension for VS 2012 which configured all blocks with a nice UI. The package is still available, but the source is not. In the long rage, we might consider something like it.

Additional context

• https://docs.microsoft.com/en-us/nuget/create-packages/source-and-config-file-transformations