Add support for Enum fields

<!-- Hi, thank you for taking the time to create an issue. Please make sure you're on the latest version of Directus. There's a chance your issue might've been resolved already 🙂 Can you please provide: 1) The issue and what you expected to happen The _ _ does _ _ when _ _ while it should _ _ 2) Exact steps to reproduce this issue Click this, tap that, see error _ _ 3) Your environment: What version of Directus you are using. Which DBMS are you using (MySQL 8, Postgres 12, ...). Which deployment are you using (npx, Docker, ...). What browser are you using (Chrome 87, Safari 14, ...). 4) Any other relevant information we might need to reproduce this issue A SQL dump of the setup. What third party services you rely on (S3, managed database, ...). --> Not allow to change or work with enum type from MySQL 8. In order to change smth for field, I need to modify settings directly in database in directus_f…