SQL Server image data type is not supported

[nj1973]

We have a customer validating SQL Server and PostgreSQL data. They have some columns of "image" data type. When working on #1577 I added a table of many SQL Server data types, the image column caused errors.

To reproduce errors we can add "col_image" back into the test constant DVT_SQL_SERVER_TYPES_COLUMNS.

FAILED tests/system/data_sources/test_sql_server.py::test_column_validation_sql_server_types - sqlalchemy.exc.ProgrammingError: (pyodbc.ProgrammingError) ('42000', '[42000] [Microsoft][ODBC Driver 17 for SQL Server][SQL Server]Operand data type image is invalid...
FAILED tests/system/data_sources/test_sql_server.py::test_row_validation_sql_server_types - sqlalchemy.exc.DataError: (pyodbc.DataError) ('22018', '[22018] [Microsoft][ODBC Driver 17 for SQL Server][SQL Server]Explicit conversion from data type image to varc...

[nj1973]

This issue needs the tests added in #1577.

[nj1973]

This is worth noting (https://learn.microsoft.com/en-us/sql/t-sql/data-types/ntext-text-and-image-transact-sql?view=sql-server-ver17):

The ntext, text, and image data types will be removed in a future version of SQL Server. Avoid using these data
types in new development work, and plan to modify applications that currently use them. Use nvarchar(max),
varchar(max), and varbinary(max) instead.

For this reason it's probably not worth investing a lot of effort into supporting image. Any easy wins can be implemented but it would also be okay to skip them.

Perhaps we have a temporary change to skip them for now and keep this issue open for a future effort.