make length_includes_head available for arrow

[guntern]

I really appreciate the work of this library and really like using it.

I started to draw arrows, but noticed that I cannot easily draw them from start to finish. Looking whether this is an issue with matplotlib or matplotlibcpp I came across matplotlib/matplotlib#12768. And it appears that there is a suitable option in matplotlib, which is not accessible in matplotlibcpp: length_includes_head

Could this option made available in matplotlibcpp? Maybe one could implement the kwargs as it is for the plot function itself.