[step 2] Update ThreadFlow

[erikbasargin]

Describe the solution you'd like

Need to add the answers section to ThreadView

• Add a header of the answers section
• Add divider between answers (do not put a divider to PostView :))
• If the thread has accepted answer then need to show just it for the first loading (QuestionEntry.acceptedAnswerId is needed to load accepted answer asap);
  In the opposite way need to show 6 answers
• Size of an each new page is 6

Additional context

Has to be done after #81