Similar name of buttons in preview of editing answer.

Preconditions: user should have EDIT_OWN_POST permission; user should have answer post in QnA topic.

Steps to reproduce:

1. Open QnA topic with user's answer.
2. Click 'Edit' button in user's answer.
3. Click 'Preview' button.

Actual result: in preview mode button has almost identical name 'Edit answer', 'Edit', that causes misunderstanding.
Expected result: in preview mode button has different, clear for understanding names, e.g. 'Save answer', 'Edit'.