Metadata doesn't get updated until code next changes #139
Description
When you change an app's version in Bundler.toml and recompile, the inserted metadata doesn't get updated unless you update the app's source code or perform a full clean build.
It seems that SwiftPM doesn't check our linked metadata file for changes when deciding whether to skip rebuilding the main executable (which is kinda fair because we've linked it in via some sneaky SwiftPM -Xlinker arguments). We may be able to fix things by renaming each metadata object file to contain a hash of its contents at the end of its file name? My only worry with that is that it may end up triggering a full rebuild of the whole project every time the metadata changes (whereas we just want the main executable file to get relinked).