Explore other browser-based experiment frameworks

Nobody has claimed this yet.

Create a list of other systems for building or deploying web-based experiments and/or participant management (e.g. labJS, pavlovia, jsPsych, opensesame, expfactory, prolific) -
* their current capabilities & what we'd need to add
* whether under active development / what that looks like
* for experiment building - whether we think it could play nicely with being given child data, past response data, an experiment protocol document (in the appropriate format), using the Lookit API to send data back, and getting built in a docker container (process can be customized per system)
* size of userbase, & current adoption among dev folks

Goal is to then decide:
(a) which if any we want to eventually support using on Lookit in place of ember-lookit-frameplayer, and when
(b) whether it makes sense to pursue collaborative development at this point and when to revisit if not

Compare labJS, pavlovia, jsPsych, opensesame, expfactory, and prolific. For each, document capabilities, development activity, userbase and adoption, plus compatibility with child data, past responses, protocol documents, the Lookit API, and Docker-based builds. Done means the comparison supports decisions about future Lookit support and collaborative development.

Written by the indexing model from the issue text.