Update typing of typed arrays to support Wasm, and test Typed_array.Bytes

[OlivierNicole]

Note: This PR depends on #1649 and is based on top of it. The feature change consists in the last two commits. edit: #1649 has been merged.

This:

• Updates the typing of Typed_array so that they work with the Wasm backend as well
• Adds tests for the new Typed_array.Bytes module.

This is part of a series of PRs intending to reduce the diff between js_of_ocaml and wasm_of_ocaml (see ocaml-wasm/wasm_of_ocaml#47).

[hhugo]

Turning the PR into a draft until the underlying PR is merged.

[OlivierNicole]

I rebased and marked the PR as ready for review.

[hhugo]

Any idea how much breakage the change of API generates ?

[hhugo]

It seems we could now complete the api with BigInt64Array and BigUint64Array. One could do that in a subsequent PR.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt64Array

[hhugo]

The PR definitely need a changelog entry

[OlivierNicole]

Any idea how much breakage the change of API generates ?

I’m not sure. I suppose we could run an opam-health-check on the PR.

[hhugo]

@OlivierNicole, can you look at Jerome suggestion ? and rebase and squash commits ?

[OlivierNicole]

Oh, I was rebasing, but you merged before I could update the PR.

[OlivierNicole]

In any case, thank you for the review and @vouillon for the explanations!

[hhugo]

I ended up squashing during the merge