Generate ggplot instructions to facet a plot by row and/or column
Examples
x <- ReducedDimensionPlot(
FacetRowBy = "Column data", FacetRowByColData="Covariate_1",
FacetColumnBy = "Column data", FacetColumnByColData="Covariate_2")
.addFacets(x)
#> [1] "facet_grid(FacetRow ~ FacetColumn)"