Codepoint arrays and binary strings

What would you think about a PR to replace binary strings with arrays of bytes, or Buffers/typed arrays? e.g. accept arrays as input to the decoder, and produce them from the encoder.

Also, it would be nice to be able to pass arrays of codepoints to the encoder and receive an array of codepoints from the decoder instead of strings, perhaps as an option? Sometimes I need to do additional processing at the codepoint level, and it is probably a a waste of time to encode the utf8 to a ucs2 string, and then decode that again to get codepoints.

Thoughts? I'm happy to write PRs for this, just wanted to get your opinion first.

Start by reviewing the encoder and decoder entry points and the current public API. Clarify with maintainers whether byte arrays, Buffers or typed arrays, and codepoint arrays are in scope, then define the intended input and output behavior before implementation; done requires an agreed design and corresponding coverage.

Written by the indexing model from the issue text.