Add MySQL support

[Rustin170506]

I’m very interested in expanding it to include additional SQL databases.

@carllerche Do you have any suggestions? Should I try it now, or wait until the driver API and other APIs are more stable? Additionally, do you have any guidance or recommended steps for adding a new database?

I also have a question about dependencies. It seems we’re using rusqlite as the dependency for the SQLite driver. If we want to support more databases, should we consider switching to sqlx to cover most databases?

[carllerche]

Someone in Discord is working on implementing toasty-sqlx to unblock more database support: https://discord.com/channels/500028886025895936/1300487772301168640