Ran `arc upload` on:
- One file.
- Several files.
- Small files.
- Big files.
- Directories.
- Unreadable files.
- Files full of random data.
- The same file over and over again.
- The same big file over and over again.
- Artificially broke `file.allocate` and redid some of the simple cases (large/chunked aren't expected to work in this case).