[FEAT] Introduce a plugin to expose the bpmn-visualization "CSS classes API" with names as parameters

[tbouffard]

Rationale

Currently, we can do this by using the BpmnElementsSearcher to get ids from names and then call the API provided by BpmnElementsRegistry.
Having a dedicated plugin would

• provide a single API call
• test the plugin infrastructure in real life and detect issues and/or new needs

Proposal

• plugin class: CssClassesByNamePlugin (find a better name)
• plugin id: css-by-name
• methods: all CSS classes related methods from BpmnElementsRegistry

Example of usage

const cssPlugin =  bpmnVisualization.getPlugin(‘css-by-name’) as CssClassesByNamePlugin;
cssPlugin.addCssClasses('activity-name-1', ['class-1', 'class-2'])