Add flexible optimizer hints support for every setting in the optimizer_switch and more

MySQL 8 implemented hints that can be embedded into the query text (for example, in the view definition) and used to control every optimizer option available in the optimizer_switch for every table (among other hints). See https://dev.mysql.com/doc/refman/8.0/en/optimizer-hints.html for more details.

I think we should do the same, as finding and fixing every place where SET STATEMENT ... FOR may help to get good plan for some problematic view is too complex to be practical. This was already discussed as a large project in MDEV-12980.