[TF] Change APIs to use Int instead of Int32.

[dan-zheng]

Friend PR: swiftlang/swift#24012

[lattner]

This looks really great Dan!

[dan-zheng]

Ready for review.

[rxwei]

The swift-apis side LGTM. Stdlib needs some more separation of concerns that I mentioned in that PR.

[eaplatanios]

This is great! It's been very annoying having to cast between Int and Int32 all the time.

[dan-zheng]

Locally verified that all tests pass. Merging now, then testing/merging swiftlang/swift#24012.

Note: I built a toolchain and swift build almost works:

$ swift build
Compile Swift Module 'DeepLearning' (8 sources)
/Users/danielzheng/swift-dev/tensorflow-swift-apis/Sources/DeepLearning/Layer.swift:49:35: error: ambiguous use of 'inference'
        return withLearningPhase(.inference) {
                                  ^
/Users/danielzheng/swift-dev/tensorflow-swift-apis/Sources/DeepLearning/Context.swift:28:10: note: found this candidate
    case inference
         ^
TensorFlow.LearningPhase:3:10: note: found this candidate
    case inference
         ^
/Users/danielzheng/swift-dev/tensorflow-swift-apis/Sources/DeepLearning/Layer.swift:60:35: error: ambiguous use of 'inference'
        return withLearningPhase(.inference) {
                                  ^
/Users/danielzheng/swift-dev/tensorflow-swift-apis/Sources/DeepLearning/Context.swift:28:10: note: found this candidate
    case inference
         ^
TensorFlow.LearningPhase:3:10: note: found this candidate
    case inference
         ^

If LearningPhase.inference is explicitly qualified, swift build succeeds.