Suggestion: Flags to specify log level on 'develop'

Issue: Warnings are spammed in the build terminal
```
WARN: "app" is not in the current scope, so it is being read from the parent scope.
This will not happen automatically in an upcoming release. See https://canjs.com/doc/can-stache.scopeAndContext.html#PreventingScopeWalking.
```

While handy for something to address in due time, it also spams so many of them that I can't see if any actual errors are occurring. Can there be a flag in the run command where the developer can specify what level of logging they desire?

Something like: `done-serve --develop --log-level error` or `done-serve --develop --log-level warn`

Start at the done-serve command entry point and trace how the --develop option configures logging. Check how warnings and errors are currently emitted; done should accept --log-level error or --log-level warn and filter output accordingly.

Written by the indexing model from the issue text.