API: rename DataFrame.applymap -> DataFrame.map

[topper-123]

I propose deprecating DataFrame.applymap and move its functionality to a new DataFrame.map method. The name map will better communicate that this is the DataFrame equivalent of Series.map. The current name can IMO be a bit confusing because the name contains both "apply" and "map", while just having "map" is clearer IMO.

See a discussion on this here.

CC @rhshadrach

[TeoSkondras]

take

[topper-123]

Hi @TeoSkondras. Thanks for wanting take take this, but I've made a branch already that is about to be ready to push to the pandas repository, so maybe not a good use of time to make a second pull requests on this.

[attack68]

If this gets picked up pls ping me, since Styler.applymap would probably be better off remaining synchronised.

[topper-123]

I've already made a PR (#52364) on this. Seem logical that the styler method has the same name as the frame method. I will ping you when this is merged no problem.

[topper-123]

This has been merged now in #52364 @attack68.