Create a CHS-jsPsych video-assent plugin

[becky-gilbert]

TL;DR

We need to create a CHS-jsPsych video-assent plugin that researchers can use to record older children's agreement to participate.

Narrative

As a researcher, I need an easy way to include the standard CHS video assent survey, ideally without much custom programming or large chunks of copy/pasted code.

Acceptance Criteria

• Tests
• Documentation
• Scoping: decide how similar this plugin needs to be to the EFP video-assent frame in terms of content and functionality
• Child can agree to participate by selecting from a yes/no multiple choice question, and/or answering verbally with video recording

And depending on scoping decisions:

• Plugin shows one or more 'pages' of text/images/audio/video/webcam content, which the participant can navigate with back/forward buttons
• Participant must view every page before they can assent
• Researcher has the option to record video during the whole procedure or just the last page
• Conditionally show this trial only to children who meet the age requirement (set via the minimumYearsToAssent parameter)