API for pessimistic locks (`SELECT … FOR UPDATE`)

Hi, there!
There is any plans to implement some locking api for spring r2dbc (may be with R2dbcEntityTemplate)
as it was in classic spring data jpa like this
```
@Lock(LockModeType.PESSIMISTIC_WRITE)
List<User> findByLastname(String lastname);
```

And of course, would be glad to see any examples of workaround to implement pessimistic locking used current version of spring-data-r2dbc