feat: chunk upload support

[alexsasharegan]

Fixes #57

[alexsasharegan]

You're right--the chunkify function should probably add something like ${vtFile.name}--chunk-${chunkIndex}.jpg. I will probably make it a function you can supply to generate the names, but that's what the default will do.

I don't plan on the chunked uploads counting for more than one file, primarily because this is easy for us to try use. I'm going to lean on you a little to test it and see if that works well. The original file will be in the list. Hopefully I can figure out a sane way to aggregate their progress.

[rrgahan]

I messaged you on Messenger about testing

[alexsasharegan]

What is that? If it's facebook messenger, I never go in there. You can email me at alex.joseph.regan@gmail.com

[alexsasharegan]

Did a basic test, and the way this is working may or may not be traditional chunking. Instead of sending one chunked xhr, I'm sending parallel xhr's (up to the browser's limit) for each chunk. Is this correct? It seems advantageous even if it's not true chunking.

The formdata added the additional chunk metadata, but one caveat with sending it in formdata is that everything is sent as strings. Below is the $_POST body that php parsed from one of the chunked uploads echoed back in the client response for me to inspect.