CB-5111 Optimize plugman action-stack module for future platforms

[SomaticIT]

Avoid static platform detection in action-stack module :

1. Create a parseProjectFile function on every platform module which need it.
   1. Ensure this function return an object containing a write function which save project file(s)
   2. Remove switch case and detect if parseProjectFile exists
   3. Remove static indexOf in loop by testing project_files variable

Only iOS has a different function name so :

1. replace this functiom name in all references.
2. add a write function to result which save both pbx and xcode files

[bshepherdson]

LGTM. Merging.