Figure out the wrappers config API

[0gust1]

At the hearth of the lib, there are wrapper components whose responsibility is to:

• initialize molstar
• handle the <canvas>
• and make the molstar instance available to subcomponents (through setContext() and getContext()).

In order to do some custom things, like implementing custom Themes/coloring (example: AlphaFold plddt confidence), the molstar instance should register custom "presets" (molstar concept is still unclear right now), at the right time, before an attempted usage.