Charts Switcher for Chart widget

[dsuren1]

Description

That's something similar to what implemented for the Map Switcher in #575. It is requested to provide a new feature to Chart widgets in MapStore dashboards to allow switching between multiple charts in a single Chart widget.

Acceptance criteria

• A kind of dropdown on top of the Chart widget allow to switch between different pre-configured charts. the same implemented for the Map Switcher
• It will be possible to activate this function and to select the list of charts during the Chart widget creation/editing
• The connection capabilities with other widgets at chart widget level will remain the same so that existing functionalities should continue working also when the widget switch over another chart selected by the user
• The Chart Switcher will be implemented as part of the Chart widget wizard, where there will be an option, a kind of plus button maybe in the toolbar, to define a list charts. The button, if clicked, will bring the user again at the first step of the wizard where it is possible to choose the layer and configure a chart for it. If more than one chart are created following this procedure a dropdown appears also in he wizard to allow the selection of the chart to see change its configuration
• If one or more charts are selected, the chart switcher will appear automatically both in the wizard and in the widget in the same way of the what implemented fir #575

Other useful information

Ref: https://github.com/geosolutions-it/MapStore2-C040/issues/624

[dsuren1]

Revised steps in multi-chart widget
https://github.com/geosolutions-it/MapStore2-C040/issues/624#issuecomment-1259094866