test(csharp/test/Drivers/Interop/Snowflake): Add testing for CAST fun…

…ctions (#1467)

Adds test for C# interop layer for the Snowflake driver on the CAST and
TO_* functions.
* Used the explicit TO_* functions instead of the generic CAST function.
* Ignored many TO_* variants which were aliases for the same function.

Includes tests for the following cast functions.

- [X] TO_DOUBLE
- [X] TO_BOOLEAN
- [X] TO_NUMERIC
- [X] TO_VARCHAR
- [X] TO_OBJECT
- [X] TO_ARRAY
- [X] TO_VARIANT
- [X] TRY_TO_NUMERIC
- [X] TRY_TO_TIMESTAMP
- [X] TRY_TO_BOOLEAN