evidence of prior crimes, wrongs, or acts under Rule 404(b) of North Carolina Rules of Evidence; probative value of 404(b) evidence not outweighed by danger of unfair prejudice or confusion of jury under Rule 403 of North Carolina Rules of Evidence; no abuse of discretion in determining authenticity of disputed text message communications; review of authentication ruling on motion in limine; no prejudicial error in failing to exclude evidence of victim's good character where no objection raised at trial