[Fix]: Ensure MCP handles parameters properly

[JerryNixon]

Desired behaviors

1. Parameter names and types always come from SQL Server metadata. Config cannot override them.
2. required can only come from config. SQL Server's metadata is always 0 for stored procedures, so metadata cannot determine this. Without config, all params appear required.
3. Default values can only come from config. SQL Server's is always NULL for stored procedures. Without config, all params appear NULL.
4. Descriptions can only come from config. SQL Server metadata has no description field for parameters or procedures. Without config, all params appear string.Empty.
5. If the config excludes a param, it is still discovered from metadata (name and type only), and will be required, have NULL default, and no description.

[Aniruddh25]

Corrections:
2. We can infer required from SQL Server metadata if the parameter is NOT NULL. Nullable parameters are not required. So, specifying required in the config is only meant to override what SQL metadata says if we still want to keep it.
5. If the config excludes a param, it is still discovered from metadata (name and type only), will be required if it is defined as NOT NULL , have NULL as the default otherwise, and no description.