add age restriction field to Player data

[MikhailDeriabin]

• [x] Add a boolean optional field for representing whenever the Player is under or over 13 years old. It's default value should be null, that means that Player did not answer the question about his/her age.
• [x] Update all DTOs for player with this field
• [x] Add authorization rule for all /chat endpoints to restrict everyone under 13 to use them