grass.jupyter: Ensure width and height in InteractiveMap are integers

[cwhite911]

The users input wasn't getting checked here causing the query to fail if the user defined the width parameter as a string.

The code below would render the map and fail when the query_vector tried to return.

m = gj.InteractiveMap(width="500", map_backend="ipyleaflet")

[petrasovaa]

This should be solved in InteractiveMap constructor. Simplest would be to do:

        self.width = int(width)
        self.height = int(height)

and let it throw the exception.

[cwhite911]

This should be solved in InteractiveMap constructor. Simplest would be to do:

        self.width = int(width)
        self.height = int(height)

and let it throw the exception.

That makes sense.