Make some LazyTensor properties @usableFromInline

[bgogul]

No description provided.

[rxwei]

Is there a reason more things need to be @usableFromInline? Public linkage was only necessary for GPE, transitively required for code serialization. Instead of adding more public symbols, I think we should clean up the @inlinable and @usableFromInline's from our library.

[bgogul]

Is there a reason more things need to be @usableFromInline? Public linkage was only necessary for GPE, transitively required for code serialization. Instead of adding more public symbols, I think we should clean up the @inlinable and @usableFromInline's from our library.

Unfortunately, this is a consequence of already having @inlinable in some parts of the TensorFlow library. In a downstream PR, I am using these in a function in Runtime.swift that is marked as @inlinable. We have https://bugs.swift.org/browse/TF-513 to clean up inlining-related annotations.