Track new features and fixes to positions in 'ggplot2' (== 4.0.0)

[aphalo]

'ggplot2` (== 4.0.0): (issue numbers are for 'ggplot2'. Information from NEWS.md

• position_dodge() and position_jitterdodge() now have a reverse argument (@teunbrand, #3610)
• Position adjustments can now have auxiliary aesthetics (@teunbrand).
  • position_nudge() gains nudge_x and nudge_y aesthetics (#3026, #5445).
  • position_dodge() gains order aesthetic (#3022, #3345)
• position_dodge(preserve = "single") now handles multi-row geoms better, such as geom_violin() (@teunbrand based on @clauswilke's work, #2801).
• position_jitterdodge() now dodges by group (@teunbrand, #3656)
• geom_point() can be dodged vertically by using position_dodge(..., orientation = "y") (@teunbrand, #5809).
• Fix a bug in position_jitterdodge() where different jitters would be applied to different position aesthetics of the same axis (@teunbrand, #5818).
• Fixed bug in position_dodge2()'s identification of range overlaps (@teunbrand, #5938, #4327).

Teun has done a lot of work on the positions. Some of these may just work as we call 'ggplot2' functions in at least some cases. In other cases where code is a modified version of the code in 'ggplot2', editing will be needed.

We need to simualtaneously look into #56 to fix the lack of support for orientation in some of our positions together with adding the new fixes and features.