Compatibility with incoming ggplot2 changes

[teunbrand]

Hi Carson and other maintainers,

Apologies for the cold PR! While building a new feature in ggplot2 we found through reverse dependency checks that {plotly} was negatively affected by the changes we'd like to implement. The new feature makes extensive use of computed values in the Geom$default_aes field, contrasted by mostly fixed values in the current CRAN version. Mostly, this PR resolves the relevant defaults before using them in {plotly}. The changes herein should be backwards compatible (locally tested with ggplot2 3.5.1).

In addition, a small change with regards to label setup is sneaked in for good measure. If you rather have a separate PR for that I'll prepare one.

We don't intend to release a new version of ggplot2 this year, so there isn't much of a hurry to merge this.