`ReadonlyArray` should be transform into `JS.ReadonlyArray`

[Maxime Mangel]

TypeScript documentation:

type A = ReadonlyArray<string>

translates into

type A = JS.ReadonlyArray<string>

In order to do that we need Fable.Core or Glutinum.ES5 to be have ReadonlyArray types defined in them.

For now, it is mapped to ResizeArray to make the code compile and kind of works. But this is an incorrect way of mapping it.

Example of npm package using this features: