Add more to confusables list

U+04FB (ӻ) to f
U+050F (ԏ) to t
U+050B (ԋ) and U+0527 (ԧ) to h
U+0437(з) and U+04E1(ӡ) to 3

Add tests for the above entries and tests for ASCII-digit spoofing.

Bug: 816769,820068
Test: components_unittests --gtest_filter=*IDN*
Change-Id: I6cd0a7e97cd0ec2df522ce30f632acfd7b78eee2
Reviewed-on: https://chromium-review.googlesource.com/962875
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543600}