`scale_fill_gridpattern()`

[trevorld]

• There are a bunch of {ggplot2} fill color scales e.g. scale_fill_brewer(), scale_fill_distiller(), scale_fill_gradient(), scale_fill_grey(), scale_fill_hue(), scale_fill_viridis(), ...
• Now that {ggplot2} and {ggpattern} support pattern fills should we provide scale(s) of {gridpattern} patternFill() pattern fills?
• We may want a variety of these...?
• And perhaps scale_pattern_fill_gridpattern() ggpattern#119 since {ggpattern} supports patterned pattern_fill values...