Test GetBytes with null buffer

[bricelam]

Another one of those de facto behaviors is that calling GetBytes with a null buffer will return the length of the data.

[bgrainger]

This should already be tested here:

AdoNetApiTest/src/AdoNet.Specification.Tests/DataReaderTestBase.cs

Lines 583 to 587 in ae131aa

	[Fact]
	public virtual void GetBytes_returns_length_when_buffer_is_null() => TestGetBytes(reader =>
	{
	Assert.Equal(4, reader.GetBytes(0, 0, null, 0, 0));
	});

[bricelam]

Doh, I searched for it too...