revamp the selection of indexes to move the bulk of the costing into
BaseIndex.
In the process, clean it up and modify the costing so that when using a
covering index, we pick the index with the least number of columns.
Smaller indexes are faster to load, leading to lower retrieval costs.

OptimizerHints dropped in favor of SET FORCE_JOIN_ORDER

when we can satisfy a query from an index without touching table data,
then that index should have a lower cost than an index that DOES need
to retrieve table data

OptimizerHints dropped in favor of SET FORCE_JOIN_ORDER setting, fixed join order in case of TableFilter reorderings by Parser, added more tests.

method

Sub-query or view cost could be wrong for cached ViewIndex

Batched index lookups for sub-query