File Input: Support larger file uploads

### Description

As a follow on task for https://github.com/FlowFuse/node-red-dashboard/pull/981

We want to chunk files selected in the client, and re-build them on the server-side to allow for file uploads greater than the maximum payload size for a given socket connection.

It would also provide clearer upload progress to the client too, and prevent socket crashes.

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate