Feature request : create data URIs to get charts as PNG images

Hi,
Most of the google charts have a getImageURI() method that allows the retrieval of a PNG image encoded as data:image/ URI. See https://developers.google.com/chart/interactive/docs/printing

It would be nice if the tags in the taglib could have an attribute like "data-uri=true" that would produce the URI string instead of generating the graph itself.

That would allow for example to embed a graph in an email. Sorry if the plugin already does this but I didn't find anything mentioning it in the documentation.

Start with the chart taglib entry points and the Google Visualization getImageURI documentation linked in the issue. Trace how a tag currently renders its graph, then evaluate the proposed data-uri=true behavior for returning a data:image/ URI suitable for email embedding. Done means the behavior is implemented and its usage is documented.

Written by the indexing model from the issue text.