When a framework that outputs Build Output API v3 specifies the `cache`
property in the `config.json` file then static-build will include those
files in the `prepareCache()` function result.
Adds detection logic for a framework / build script outputting Build Output v3
format to the filesystem. In this case, `static-build` will simply stop processing
after the Build Command since deserialization happens in the build-container side
of things (this is different compared to the v1 output which gets handled in this
Builder. The reason for that is because the v3 output matches what `vc build`
outputs vs. v1 which is a different format).