new sync IO api

[mikea]

This change reworks all synchronoush IO API in terms of ArrayPtr to be safer.

Read API now is:

  size_t read(ArrayPtr<byte> buffer, size_t minBytes);
  virtual size_t tryRead(ArrayPtr<byte> buffer, size_t minBytes) = 0;
  inline void read(ArrayPtr<byte> buffer) { read(buffer, buffer.size()); }

and new write API supports multiple pieces from the get go:

  virtual void write(ArrayPtr<const byte> data, 
                     ArrayPtr<const ArrayPtr<const byte>> moreData = nullptr) = 0;

[mikea]

I think this is ready for review. I'll start working on downstream PRs meanwhile.

[kentonv]

Looks like the MSVC tests are failing. (#2024 fixed them at master, so presumably it's a new breakage.)

Otherwise looks good.

[jasnell]

LGTM once CI is green. I'll leave it to someone else to actually hit approve tho.

[mikea]

Looks like the MSVC tests are failing. (#2024 fixed them at master, so presumably it's a new breakage.)

Windows build is fixed. I've opened downstream PRs that I will update now to the latest hash:

• new capnp sync IO API cloudflare/workerd#2107
• EW 7902

[mikea]

just a rebase