HPCC-10461 Add additional plugins for external databases

Added sqlite plugin as a POC

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
HPCC-10461 Add additional plugins for external databases

Added initial version of MySQL embed support

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
HPCC-10461 Add additional plugins for external databases

Additional MySQL fixes, including lazy streamed inputs, and minor fixup
spotted in code review.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
HPCC-10461 Add additional plugins for external databases

Minor fixes from code review.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #5223 from richardkchapman/sqlite

HPCC-10461 Add additional plugins for external databases 

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>