added privacy provider, including lti launch details

[mrblippy]

Checklist

• [x] the contributor license agreement is signed
• [x] commit message follows commit guidelines
• [x] screenshots are included showing significant UI changes
• [x] documentation is changed or added

Description of change

https://github.com/openequella/moodle-mod_openEQUELLA/issues/49

This commit implements the Moodle privacy api. In particular defining what personally identifiable details are sent through to oEQ during an lti launch.

This can be viewed via Site administration->Users->Privacy and policies->Plugin privacy registry->Activity Modules

The majority of the Privacy api methods have been left implemented, as oEQ does not store any personally identifiable moodle user details.

[edalex-ian]

Heya @mrblippy

Just to keep this one moving, I've made the tweaks mentioned and will merge in. ;)