[Android] Add bsazonov@ to firstrun OWNERS

This CL changes OWNERS for Android FRE Java files:
1. Adds bsazonov@ to OWNERS.
2. Links OWNERS in javatests and junit folders to OWNERS in java folder.

Bug: None
Change-Id: I1358fe3c015763de46f4f3a09d00d6b3aab83897
Reviewed-on: https://chromium-review.googlesource.com/1019441Reviewed-by: Ted Choc <tedchoc@chromium.org>
Commit-Queue: Boris Sazonov <bsazonov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553333}

chrome/android/java/src/org/chromium/chrome/browser/firstrun/OWNERS

+bsazonov@chromium.org
 pkotwicz@chromium.org
 yusufo@chromium.org

chrome/android/javatests/src/org/chromium/chrome/browser/firstrun/OWNERS

+file://chrome/android/java/src/org/chromium/chrome/browser/firstrun/OWNERS

chrome/android/junit/src/org/chromium/chrome/browser/firstrun/OWNERS

+file://chrome/android/java/src/org/chromium/chrome/browser/firstrun/OWNERS