GeomBar should use rename_size = TRUE

[yutannihilation]

During comparing GeomBar and GeomCol on #4921, I found GeomBar doesn't have rename_size = TRUE specified.

I think we can just add rename_size = TRUE to GeomBar and replace GeomCol with GeomCol <- ggproto("GeomCol", GeomBar) as a first step towards #3798

[thomasp85]

good catch - do you want to take this?

[yutannihilation]

Yes, I'll make a PR after #4921 gets merged.