Generate JSON schema of flow action definition

[debovema]

What kind of change does this PR introduce? (check one with "x")

[] Bugfix
[] Feature
[] Code style update (formatting, local variables)
[x] Refactoring (no functional changes, no api changes)
[] Other... Please describe:

Fixes: #

What is the current behavior?

What is the new behavior?

This adds the automatic generation of the JSON schema of a flow action definition.