create sign up(anketa) page

[ihor-bobyr]

create https://programming.org.ua/en/anketa (first step)

• [x] render all inputs
• [x] add simple validation
• [x] validate age of user and navigate correctly
  • [x] >= 17 yo -> anketa/adults
  • [x] >=12 && < 17 yo -> anketa/teens
  • [x] < 12 yo -> show warning and stay on the page

[k-boiko]

I think we will just create different pages for each step so I will update the description of this issue to be only about first step of sign up

[ihor-bobyr]

reset isVisited local storage flag for https://github.com/shpp/programming.org.ua/issues/53