Remove platform-centered workflow support

ref: [[1]](https://cordova.apache.org/docs/en/latest/guide/platforms/ios/#platform-centered-workflow)

_(seems to be in very limited use)_

As discussed in and :

- known to be broken on Android for a number of years
- known to be affected by Python 2 vs 3 incompatibility, needs a workaround such proposal in apache/cordova-ios#769
- documentation known to be outdated for iOS
- lack of resources that would be needed to get this functionality working correctly

We would like to focus our resources on the Cordova CLI workflow, as proposed by @erisu in .

[1] https://cordova.apache.org/docs/en/latest/guide/platforms/ios/#platform-centered-workflow