Template full parsing and validation should happen during the synchronous phase of the WF

[lorenzo-biava]

A template full parsing and validation should happen during the synchronous phase of the WF (so that the deployment won't be even created if it is not fully valid).
As of now, Chronos and IM deployment services do full validation only in doDeploy method, which is invoked in the asynchronous WF phase.
We should add a dedicated method (e.g. prepareDeployment) to be invoked during the synchronous phase of the WF to fail fast.