[FEATURE]: Prisma's `updatedAt` behavior. `onUpdate` API suggestion

Problem

Describe what you want Prisma has awesome feature such as declaring a column with `@updatedAt` which updates that column with a new timestamp every time the record updates. Instead of suggesting to add something similar like just `updatedAt` alternative, what if you provide a more flexible `onUpdate` method when declaring columns in schema so we can do something like this: [code block] The idea is that this method accepts a callback function that returns a new value for the column. The callback function is invoked every time the record updates. The basic example is to use it for timestamps on `updatedAt` columns, but it can be used for anything since the new value will be the one returned by the callback. In general, when the record updates, we can find out which columns were updated, old values and new values. Maybe, this data can be accepted by `onUpdate` callback like [code block] Or any other better API for this.