MySQL dialect for Lotus.Source.Adapters.Ecto.
MySQL has no schema-within-database concept, so databases serve as
namespaces. Query plans come from EXPLAIN FORMAT=JSON, and the
statement timeout is applied as max_execution_time. There is no search
path, so set_search_path/2 is not implemented.
Read alongside Lotus.Source.Adapters.Ecto.Dialect when writing a dialect
for another SQL engine — this module is the reference implementation.