[FEAT] Provide a Minimap for diagram navigation

[tbouffard]

Is your feature request related to a problem? Please describe. Provide a minimap for navigation guidance. This is usefull when using large diagram, when the diagram has been zoom and the user wants to navigate or know where is the current position regarding the global diagram.

Describe the solution you'd like As an integrator of the lib, I would like to be able to toggle the minimap and display it in a provided html container. We should also check the impact on performance, in particular if we can disable icon rendering, labels, ... Depending on the performance results, we may decide to make these details enabled or disabled by configuration. This may be defer to a dedicated issue.

Additional context mxGraph provides support for that, a POC of the minimap has been demonstrated in #555.

The way the minimap is behaving fully depends on the css style applied to the div that hold the minimap: position, size, transparency, .... As for the regular BPMN diagram rendering, please prefer using a fixed size viewport. The POC has also shown that labels are not displayed in the minimap (at least with [email protected]) whereas the mxgraph documentation does not explicitly state that.