buffer: add Buffer.copyFrom(...)
This is a variation on Buffer.from(arrayBufferView)
that copies the bytes and does not truncate when using a multibyte TypedArray. For instance,
Buffer.from(new Uint16Array([0xffff]))
<Buffer ff>
Buffer.copyBytesFrom(new Uint16Array([0xffff]))
<Buffer ff ff>
Open to suggestions on a better name.