Need better exception for TextLoader when column attribute is not present #2037
Description
In PR #2033 we converted all uses of the legacy TextLoader to the new TextLoader.
It emerged that when reading from a file providing the schema, if there is no column attribute, then there are two different exceptions thrown depending on whether it is a debug or release build.
We need a single exception for both debug and release, and we need the name to be more informative. We also need a single message for both exceptions.
This is the test that exerts these exceptions: ThrowsExceptionWithPropertyName in TextLoaderTests.cs