Use standard SQL (not MySQL-specific extensions) for database support

Re-roll #5 🐛 Support for non-MySQL DBs Needs review to be compatible with #3296984 Update module to be D10 compatible.

Thanks for the re-roll Aman! Updating description with some links to why MySQLisms are discouraged.

Looks good to me - we (note - I am a colleague of xurizaemon and amanp) have been using this patch on a site with postgres for several years.

Chris Burgess (xurizaemon), amanp - Thank you for your work, but unfortunately the module has undergone some changes, so we need to modify the patch.