The Android Studio Style configuration does not match the checkstyle
configuration, which causes import order to be wrong. The configuration
is specified here:
//tools/android/checkstyle/chromium-style-5.0.xml
under ImportOrder.

This CL copies the style configuration from the Android repository,
but changes it so that it matches what we have in checkstyle.

It also updates the Android Studio documentation to point to the
new file, and adds the new content and the documentation to the
watchlist for Android Studio in addition to updating the error message
from checkstyle to now refer to the new style file.

BUG=None

Review-Url: https://codereview.chromium.org/2710573004
Cr-Commit-Position: refs/heads/master@{#453542}