Added an option for a custom ProfiledDbDataReader implementation

[kekekeks]

Some ADO providers have extended API for database-specific functions, a notable example is Npgsql.

Some ORMs (e. g. linq2db) are aware of said functions and try to use them. Fortunately linq2db doesn't hardcode any type references and discovers needed APIs via reflection, it even allows to configure the expected reader type when needed.

This PR adds an option to substitute the standard ProfiledDbDataReader with a derived type that can reimplement said database-specific API.

New constructors are added to keep binary compatibility with existing code.

[NickCraver]

I see the intent here, but I think we can improve the approach. The overall issue I see is this creates a lot of complicating to overload just one of the types involved (Connection, Command, Reader, Transaction, Adapter, ProviderFactory). To have this expand to be extensible for everything would be quite a lot of code (and more than a little messy honestly).

The intent of MiniProfiler is to allow extensibility here, but the approach intent is inheritance (as MiniProfiler itself does). For example in this case could be accomplished like this:

public class MyProfiledConnection : ProfiledDbConnection
{
    public MyProfiledConnection(DbConnection connection, IDbProfiler profiler) : base(connection, profiler) { }
    protected override DbCommand CreateDbCommand() => new MyProfiledCommand(WrappedConnection.CreateCommand(), this, Profiler);
}

public class MyProfiledCommand : ProfiledDbCommand
{
    public MyProfiledCommand(DbCommand command, DbConnection connection, IDbProfiler profiler) : base(command, connection, profiler) { }
    protected override DbDataReader ExecuteDbDataReader(CommandBehavior behavior) => ...
}
// and so on...

It may be more code for a single user to have, but it's the only realistic way to override the whole tree and have something maintainable for all. Thoughts?

[kekekeks]

Switched to protected virtual extension points

[NickCraver]

The convenient method to override is 👍, let's just get the naming consistent :)

[NickCraver]

Let's align the naming here - we have CreateDbCommand with Db elsewhere and CreateDataReader here - can you please change this to CreateDbDataReader (more correct given the return type).

[NickCraver]

Looking good, thanks!

[NickCraver]

I’m away this week, but this build should be up on the MyGet feed in a few minutes for release, thanks again for finding a good solution here with me :)