This PR was merged into the 5.1-dev branch.Discussion----------[Uid] use one class per type of UUID| Q             | A| ------------- | ---| Branch?       | master| Bug fix?      | no| New feature?  | yes| Deprecations? | no| Tickets       | -| License       | MIT| Doc PR        | -(embeds#36064 for now)Would it make sense to have one class per type of UUID?This aligns the type system and UUID types, so that one could type hint e.g. `UuidV4 $uuid`.This PR does so. `UuidV1`/2/3/4 and `NullUuid` all extend the base `Uuid` class, which provides common methods and the factories needed to create each king of UUID.This means we don't need the `getType()` nor the `isNull()` methods since they can be replaced by instanceof checks.As expected,  `getTime()` and `getMac()` then now exist only on the `UuidV1` class - no need for any version check nor any `LogicException` anymore.Each type is guaranteed to contain a UUID that matches its class' type. The base `Uuid` class is used for the "no type" type.Commits-------62f6ac4 [Uid] use one class per type of UUID