Creating LCE compatible TFLite iOS apps

[arashb]

TFLite provides a collection of example mobile apps for specific DL applications. We already have a setup in place to build LCE Lite AAR to support Android (see #238) . No process (and documentation) is currently in place to support iOS. what needs to be done:

• setting up the LCE build process for iOS
• building the LCE Lite package with integrated LCE custom operators for iOS
• integrating the LCE Lite for iOS in one of TF Lite example apps and test on an iOS device

[arashb]

to create a LCE Lite package for iOS, first we need to create a LCE C API library similar to TF Lite C API. Then the LCE C API will be used in TensorFlow Lite for iOS and its swift interface.

[AdamHillier]

I have this working locally, and will make a PR to add support.