Tests: TvpMain should be split

[TvpTest](https://github.com/dotnet/SqlClient/blob/main/src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/ParameterTest/TvpTest.cs) is a large single complicated test. It's purpose isn't clear and debugging any failure within it is proving to be very difficult, first of all identifying the failure and then debugging through the bulk of working code to the site of the problem when there are thrown errors in expected situations.

This test should be broken up into smaller units if possible and those units given descriptive names so the failure reasons are readily understandable from the name.