Extend DbQuerySource to support multiple connection types:
- Add connectionType parameter ("jde", "cms", "lotfinder")
- Use appropriate IDbConnectionFactory method for each type
- Support Dictionary<string, object> parameters
- Use DbConnection/DbCommand for cross-database compatibility
Adds DbQuerySource, an IImportSource implementation that executes SQL
queries against the LotFinder database. Supports parameterized queries
using anonymous objects and configurable command timeouts.