Bump Major versions for AEP iOS 4.x support [MOB-18971]

[cdhoffmann]

Bumps the major versions of all plugins to 3.x, aligning all of the major versions. Includes:

• iOS 11 minimum deployment version, previously 10
• Bumps all iOS AEP SDK extensions to 4.x
• Adds export for data classes in core plugin as per: #26