(WIP) Studio: adding HTML5 data-* attributes for UI Testing Hooks

This work aims to use HTML5 data attributes as UI testing hooks. TODOs still include:

* identifying what elements in the UI are useful for TestEng to keep tabs on during view interaction/load  (by TestEng/UX/FED)
* creating conventions for data-* attributes based on UI types identified  (by TestEng/UX/FED)
* creating conventions for any data-* attribute state changes based on interactions  (by TestEng/UX/FED)
* documenting conventions (by TestEng/FED)
* using attributes in written UI tests (by TestEng)