Calling some methods on `DateTime` should set proper format on resulting schema

[romalytvynenko]

Carbon ones:

toDateString -> date toDateTimeString -> date-time format('Y-m-d') -> date format('Y-m-d H:i:s') -> date-time

Something else?

[alecpl]

There's a few returning an integer in https://carbon.nesbot.com/docs/#api-getters e.g. getTimestamp() -> int, but most probably rarely used in APIs.