Provide factory to map from (coffee, notation) to workflow model

[martin-fleck-at]

• Provide mapping for coffee example to workflow model elements
• Provide convenience builder for workflow model elements
• Use builder in factory and in creation handlers

Please note this PR depends on https://github.com/eclipsesource/graphical-lsp/pull/307 so the changes look far bigger than what I actually did (for now) ;-)