Email address autolink regex updates.

This CL updates the email address pattern with:
* Local-part should be max 64 characters, and domain should be max 255
  characters (it was the opposite before).
* Labels in the domain name should be at most 63 characters.
* Support non-ascii unicode characters.
* Add tests for email address pattern.

Bug:9585450
Change-Id: I983f269904ef014ef625417dd08b6509084e6879