Add built in support for raw files.

[jjnaude]

When getting back from a survey where we captured only raw files, we often find that we have to spend many hours or days converting those files to JPGs before we can kick off the Detweb process. An earlier version of Detweb had automatic cloud based conversion of CR2 files to JPG built in to solve this issue. Two problems with this:

• This functionality has not been ported.
• We have switched to using Sony mirrorles cameras from our previous Canon 6Ds, so we are no longer dealing with CR2 or CR3 files but with ARWs.

The logical place to add this functionality is in the current handleUpload Lambda. This makes use of the sharp library for nodejs which in turn makes use of libvips. Some quick googling shows lovell/sharp#3612 that while the default config does not support any raw formats, a custom install could potentially solve that problem. I am currently using a pre-built lambda layer (from https://github.com/pH200/sharp-layer I think) to provide the sharp layer and understand very little about the building process. It looks like I'll have to dig into how a lambda layer is built, probably using github actions (to reuse as much as possible from my source) and hopefully it will be possible to build a layer that provides ARW support (as well as support for all other formats that ImageMagick supports)