accessibility fixes for "Connect with X" buttons
accessibility fixes for "Connect with X" buttons

- add role="button" for link because it acts like button and needed to
be announced to screen reader users with correct role
- added aria-hidden="true" for icon because this image is not meaningful
for screen reader users
- removed title=".." attribute from <img> because parent "<a>" element
already has this title, no need to duplicate

miled/wordpress-social-login,miled/wordpress-social-login,miled/wordpress-social-login,miled/wordpress-social-login