[Feature request]: selectionType functionality to enable additive selection

[hursth]

Feature request - it would be amazing to have access to the selectionType argument available in cytoscape.js (https://js.cytoscape.org/#init-opts/selectionType) that allows additive selection of nodes, rather than having to shift+click to select all nodes at once.

Thanks for the great work - this is an awesome library!

[xhluca]

Hi @hursth, is that a new feature for Cytoscape.js? If so, feel free open a PR in https://github.com/plotly/react-cytoscapejs first to add that feature!