Add function to get names of available shapes

[cgoo4]

Add a function to create a data frame of available shapes and their associated sets.

The motivation is to make it easier to add a vector of chosen shape names to scale_shape_manual().

[cgoo4]

Completed example:

library(ggfoundry)
#> Loading required package: ggplot2

shapes_cast()
#>          set    shape
#> 1     circle  circleF
#> 3     circle  circleL
#> 5     circle  circleR
#> 7  container      jar
#> 9  container     tube
#> 11     cross   cross1
#> 13     cross   cross2
#> 15      geom      box
#> 17      geom   dendro
#> 19      geom   ribbon
#> 21      geom   violin
#> 23   polygon heptagon
#> 25   polygon  hexagon
#> 27   polygon  octagon
#> 29   polygon pentagon

^{Created on 2024-05-30 with reprex v2.1.0}