Fix the preview couldn't be scrolled up and down when showing the scroll bar.

Actions:
1) Add the specific attribute to disallow parent view intercept the touch event of child view to avoid conflicting with the nested scroll view.
2) Add the scroll view into the page of the mail content preview.

Bug: 220078816
Test: manual test
Change-Id: I7f3b2afdf76e501386d9080e7a0eed8b92e28d3b