[AutoDiff] Replace SIMD use of @differentiable(jvp:vjp:) with @derivative(of:)

[bartchr808]

With the change of using @derivative(of:) as done in this PR, I started off with some parts of TF-1085 by updating SIMD.

[bartchr808]

@swift-ci Please test tensorflow

[dan-zheng]

ParseableInterface/verify_stdlib.swift fails due to TF-1094:

/Users/swiftci/jenkins/workspace/swift-PR-TensorFlow-macOS/Ninja-ReleaseAssert+stdlib-Release/swift-macosx-x86_64/lib/swift/macosx/Swift.swiftmodule/x86_64.swiftinterface:23857:4: error: function is not differentiable
  @differentiable(wrt: value where Self : Swift.Differentiable, Self == Self.TangentVector, Self.Scalar : Swift.BinaryFloatingPoint, Self.Scalar : Swift.Differentiable, Self.Scalar == Self.Scalar.TangentVector)
  ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/swiftci/jenkins/workspace/swift-PR-TensorFlow-macOS/Ninja-ReleaseAssert+stdlib-Release/swift-macosx-x86_64/lib/swift/macosx/Swift.swiftmodule/x86_64.swiftinterface:23858:24: note: when differentiating this function definition
  @_transparent public init(repeating value: Self.Scalar) {
                       ^
/Users/swiftci/jenkins/workspace/swift-PR-TensorFlow-macOS/Ninja-ReleaseAssert+stdlib-Release/swift-macosx-x86_64/lib/swift/macosx/Swift.swiftmodule/x86_64.swiftinterface:23860:14: note: cannot differentiate through a non-differentiable result; do you want to use 'withoutDerivative(at:)'?
    for i in indices { self[i] = value }
             ^
<unknown>:0: error: failed to load module 'Swift'

The reason is SIMD.init(repeating:) is serialized but SIMD._vjpInit(repeating:) is not. This causes SIMD._vjpInit(repeating:) to not be registered as a derivative during .swiftinterface compilation.

A workaround is to mark SIMD._vjpInit as @inlinable to make it serialized. We can visit a robust solution for TF-1094 later.

[dan-zheng]

@swift-ci Please test tensorflow

[dan-zheng]

@swift-ci Please test tensorflow macOS