[Improvement] widget HTML export uses native ag-grid code only

[vincent-grosbois]

This issue is to track a potential improvement on this lib.

Currently, the HTML export of ipyaggrid Grid component is based on the "automatic" export of ipywidget components to HTML ( cf https://ipywidgets.readthedocs.io/en/7.6.3/embedding.html ) . This is fine (in case it works), but possibly the generated HTML/js code is bloated/slow, because it has to embed ipywidget JS dependencies etc. In essence, when we do ipyaggrid HTML export we now have gone full circle, because we have a html/js lib (ag-grid), wrapped in python, wrapped in js, again exported in HTML :D

A possible way to improve this would be to add another HTML export method, where ipyaggrid would manually generate the "pure" ag-grid code, with only dependencies on ag-grid and not on ipywidgets