Generalize on-demand dependency loading from chart.js

[falkoschindler]

In chart.js we load various Highchart submodules on demand, i.e. only if a ui.chart is used (#211, #212). Usually we exclude unused dependencies with ui.run(..., exclude=...). But maybe we can generalize the approach from chart.js to other elements?

[falkoschindler]

See #524 for a related discussion.

[falkoschindler]

@dclause is working on it: #658 💪