Add private r2 bucket

[davidharting]

Create very basic example endpoint to demonstrate to myself that I have object storage working.

Lessons learned:

• I initially limited my r2 token to the static IP of my DO VM. However, to Cloudflare, the request did not appear to come from here
• GET visibility requests are not implemented on r2 like AWS. So calls to Storage::()->getVisibility('some-file') caused 500s
• The default disk config has throw => false. This means Storage calls return false instead of throwing if something goes wrong. I switched to raise Exceptions.

While I was iterating and testing in prod (hey it's okay it's just my own little VM and site!), I found it much easier to cross-build for my VM from my host machine. So I ended up with a flow where I would build, then save it to a tar file (TIL about docker save!), and then scp it to the VM and docker load it there.