be careful about truncated multi byte strings

[romainfrancois]

closes #63

There's probably a better way to handle this but the situation described in #63 is that openai_stream_ide_delta() receives a byte stream that is truncated in the middle of a multi byte string, which is common when you use emojis, etc ...

So what this does is store the raw bytes in ch_env$stream$bytes, parse the whole thing, and holistically try to nchar() the rawToChar()ed string until there is no error.

[romainfrancois]

With this, I can get the golem poem:

> chattr::chattr("Can you write a poem about the R package called 'golem'. Please add a bunch of emojis.")
Sure! Here's a poem about the R package 'golem' with a bunch of emojis:

🌟 In the land of R, a package was born,
🔧 Its name was 'golem', a tool to adorn.
🏗️ With 🧱 and 🏗️, it built apps with ease,
🌈 Adding colors and interactivity, oh please!

📦 'Golem' wrapped up shiny, like a gift,
🎁 Making web apps with a magical lift.
🌐 It brought the power of the web to R,
🖥️ Creating interfaces that would take you far.

🔮 With 'golem', you could create something new,
🎨 Designing apps with a beautiful view.
📊 Visualize data with 📈 and 📉,
🔍 Explore insights with a few clicks and scrolls.

🔒 'Golem' kept your code safe and secure,
🔐 Protecting your app with a strong allure.
🔧 It handled dependencies with care,
📦 Ensuring your app would always be there.

🚀 So, let's embark on a 'golem' adventure,
🌠 Building apps with joy and rapture.
🎉 With emojis and code, we'll create something grand,
🌟 'Golem' in our hands, a magic wand.

Note: The poem is for entertainment purposes only and does not provide any code or technical information about the 'golem' package.

[romainfrancois]

I would argue now this is a missed opportunity in httr2. I'll send a PR there.