grass.jupyter: Add SeriesMap and tests

[chaedri]

Based off TimeSeriesMap, SeriesMap creates a ipywidgets Slider for scrolling between a list of rasters and/or vectors.

series = gj.SeriesMap(height = 500)
series.add_rasters(["elevation_shade", "geology", "soils"])
series.add_vectors(["streams", "streets", "viewpoints"])
series.d_barscale()
series.show()  # Create Slider

[chaedri]

Outstanding questions for this PR:

• There's some duplicate code here with TimeSeriesMap; should there be shared functions between them?
• This is not the most efficient way of doing this but I'm not sure of a better way.
• Vector styling should be improved

[chaedri]

Replaced by #3036