Add proper DSL schedule support "on" at workflow base and timeouts on tasks

[ricardozanini]

What would you like to be added:
Although we already have support for schedulers, we are lacking proper support for the DSL. See spec: https://github.com/serverlessworkflow/specification/blob/main/dsl-reference.md#schedule

Basically, we need the on for Workflow base and timeouts on the tasks. Step is a great interface to add it.

Why is this needed: