CDK-451: View isReady / signalReady

This PR builds on https://github.com/kite-sdk/kite/pull/98 and https://github.com/kite-sdk/kite/pull/99 adding support for isReady / signalReady on Views.
The logic to resolve the root and signal dir should be done once and used by both `signalReady` and `isReady` to avoid incompatibility later.