[HTMLViewer] Explicitly set WebSettings#setAllowFileAccess to true am: d1349e757f am: 6a57196481 am: 2ceb86e2ed

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/HTMLViewer/+/10426766

Change-Id: Ieea1bfa0a9156294436ddb3fea2e4c90edb14eaf