Fix catboost to work with `has_time`

[alex-hse-repository]

🚀 Feature Request

We need to reorder the points in the dataset, which is passed to the catboost model to make it able to use has_time parameter properly.

Proposal

Sort df by the "timestamp" column in the first line of the following methods:

• https://github.com/tinkoff-ai/etna/blob/0bb7a64e22c06d767536f58aded2126d08936f1f/etna/models/catboost.py#L38
• https://github.com/tinkoff-ai/etna/blob/0bb7a64e22c06d767536f58aded2126d08936f1f/etna/models/catboost.py#L61

Test cases

No test cases required

Additional context

No response