Better zoom/pan tools

[maximlt]

In general the UX should be improved compared to dash-doodler when it comes to zooming and panning an image while doodling it. For instance the zoom should be preserved when using widgets; currently often lost in dash-doodler.

A tooltip zoom could be a nice addition to the app. However, since this is not yet available part of the Holoviz/Bokeh, building one from scratch is likely out of reach for this Anaconda project.

Yet with the existing tools we could get something close to what a tooptip zoom would do. E.g. we can easily make it so clicking in the main window re-centers a separate zoom window, where you could then do your editing. We would have to assess though how useful that would be, before starting implementing it. We could get some inspiration from other cartographic tools, such as QGIS.