* Highlight SSO in register and login pages
* Highlight SSO in home page
* updated split test request to new APIs
* reordered SSO buttons when highlighting SSO in login
* Updated copy for institutional login and fixed indentation
* increased SSO button size in homepage for highlight-sso variant
* prefill email in registration page
* added `register` and `register-success` events
GitOrigin-RevId: 2822afc15c27856ca713002ed804e1f42a2d955c