Should we do multipart uploads internally?

[nikeee]

Bun has a feature that it uses multipart uploads for file.write instead of PutObject if some conditions are met. The goal is to upload a file using multiple streams in parallel.

This might be unexpected and fail if the used service does not support multipart uploads.

There might also be some random restrictions by the server. For example, CF R2 requires all parts to be the same size and >=5MiB (except the last one). We could hard-code these limits but it might fail if some other provider decides to have some other limit.

Maybe we can offer an option to enable that kind of behaviour?