[DEV] Testing upgrades

James has a built-in upgrader, which means users are less likely to be manually watching for newer releases. So, we should be confident that we don't release a version of James that no longer updates properly.

Three platforms should be tested:

• Linux (testable by @mitchhentges)
• Mac (testable by @nerdbeere and @mitchhentges)
• Windows (testable by @tomitm and @mitchhentges)

How to upgrade-test:

1. Install an HTTP file server like serve
2. Create a "future" build of James to upgrade to
   1. Update version in package.json (bump by two versions)
   2. npm run dist-upgrade-test (or dist-upgrade-test:win64 on Windows)
   3. Copy then contents of binaries to a new folder (outside of james repository)
   4. Within the new folder, run an HTTP file server on port 9000 (serve -p 9000)
3. Create a "future" build of James to upgrade from
   1. Update version in package.json (bump back to the expected version of the new release)
   2. npm run dist-upgrade-test (or dist-upgrade-test:win64 on Windows)
4. Run the correct binary in binaries
5. Ensure that the status is shown properly in the bottom-right of James, and that the update completes correctly