Redirect to _system target every external link

# Feature Request

## Motivation Behind Feature
Using new WebViews means not being able to access iFrame due to CORS limitations.
Links inside iFrames will be opened inside inAppBrowser causing some problems on back or breaking system intents.

## Feature Description
It will be great to have a setting to force all links to be redirected in "_system".

## Alternatives or Workarounds
By now I was unable to find a workaround.

Start from the inAppBrowser handling described in the issue and compare behavior across the affected WebViews. Verify that the proposed setting redirects every external link to "_system" without breaking back navigation or system intents.

Written by the indexing model from the issue text.