Validation of tasks transitions graph

**Is your feature request related to a problem? Please describe.**
Currently definition of the tasks transitions graph is a time consuming process that is error prone. If developer makes a typo, he / she has no real indicator that he made an error.

**Describe the solution you'd like**
It would be good to validate transitions graph either during build time on Knot.X startup, to ensure, that all the edges of the graph exist.

**Describe alternatives you've considered**
N/A

**Additional context**
Currently if developer makes a typo while creating a configuration for tasks, he / she has no indicator about incorrect configuration until given transition is executed. The goal of this task would be to create a mechanism that would validate if all the edges of the transitions graph do exist.
For example, currently if there is a transition to non-existing action, there is a runtime issue logged in Knot.X logs:

> i.k.f.handler.action.ActionProvider - Could not create initialize proxy [ACTION-NAME] with missing config.

Start by tracing how the tasks transitions graph is loaded and how ActionProvider reports a missing action; the issue provides no file or test names. Define completion as detecting every edge that points to a nonexistent action during build or Knot.X startup, rather than only when the transition executes.

Written by the indexing model from the issue text.