Check that Mahara is compliant with Universal Acceptance rules

[Robert Lyon]

Universal Acceptance is a foundational requirement for a truly multilingual Internet, one in which users around the world can navigate entirely in local languages. It is also the key to unlocking the potential of new generic top-level domains (gTLDs) to foster competition, consumer choice and innovation in the domain name industry. To achieve Universal Acceptance, Internet applications and systems must treat all TLDs in a consistent manner, including new gTLDs and internationalized TLDs. Specifically, they must accept, validate, store, process and display all domain names.

Mahara does save domain names in some places eg $cfg->wwwroot or profile web address
and Mahara does rely on email addresses so we should make sure those places are compatible.

The guidelines: https://uasg.tech/wp-content/uploads/2016/06/UASG005-160302-en-quickguide-digital.pdf

Testing punycode: https://www.punycoder.com/

An example: http://xn--mori-qsa.com is a valid domain that translates to http://māori.com/
Can we handle it and/or can we display the link as māori.com ?