Replace Stream#_transform()s with single method with chunk: any

[chbrown]

When a stream.Transform is fed from a stream that has {objectMode: true}, the Stream#_transform(chunk, encoding, callback) method will not be called with chunks that are strings or Buffers.

Simply adding a _transform() variant with chunk: any does not satisfy the TypeScript compiler for some reason.

I'd prefer type parameterizing the whole stream.Transform class with the type of the chunks it will deal with, but this change is smaller, and, I imagine, less contentious.

[vvakame]

@jvilk @loyd could you review this PR?

[loyd]

@chbrown The same as _write, write, writev, unshift, and end.

[chbrown]

@loyd I guess I only wanted to venture as much as I needed for my library to compile — but yes, those suffer the same problem. Would you approve a PR changing them all?

[loyd]

@chbrown Well. I think, until TS supports default generic type or has strong type inference (like rust or haskell), parameterizing leads to "visual" overhead (it will always need to specify the type explicit) and I am inclined to any solution.

[chbrown]

@loyd I agree. I've made the rest of the changes. It turns out a few of the chunk: T argument types were already any, e.g., Readable#push. Let me know if I missed any.

[loyd]

@vvakame LGTM

[vvakame]

@loyd thanks!
@chbrown thanks mate! 👍

[jvilk]

Thanks for reviewing, @loyd! I was on vacation, but am back now. 😄 I hope we can eventually have better support for typing things as string | Buffer without inconveniencing code writers.