Disable save tool when using map tiles

[philippjfr]

When using map tiles the browser prevents the save tool from working because the cross-origin requests, the developer console says the following:

Uncaught DOMException: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported.

There is likely nothing that can be done about as described in this StackOverflow post, which means we should disable the save tool if a tile source is used.