Add optional parameters to customize the measure tools vector features

As for now it is not possible to adapt the layout of the features drawn on the map when using measuring tools.

This PR adds support of 2 new Measure plugin's configs. For instance:
```
    {   
        ptype: "cgxp_measure",
        actionTarget: "center.tbar",
        symbolizers: {
            "Point": {
                pointRadius: 10, 
                graphicName: "square",
                fillColor: "blue",
                fillOpacity: 1,
                strokeWidth: 1,
                strokeOpacity: 1,
                strokeColor: "red"
            }   
        },  
        sketchSymbolizers: {
            "Point": {
                pointRadius: 10, 
                graphicName: "square",
                fillColor: "orange",
                fillOpacity: 1,
                strokeWidth: 2,
                strokeOpacity: 1,
                strokeColor: "red"
            }   
        },  
        toggleGroup: "maptools"
    },
```