[FEATURE]: Support MySQL 5.7

### Describe what you want

What are the chances of adding/maintaining support for MySQL 5.7?

Drizzle 0.26 worked but the 0.28 (primarily lateral joins from what I can see) removes support for 5.7.

I've tried the "planetscale" mode but this does not work - it removes lateral joins specifically but appears to maintain the column reference which the lateral join allows (I may have misinterpreted).

Thanks