#397

#401

- Basic implementation

This reverts commit f90bcc5b
Target installation seems not to support this Verona Api version yet

- Rewrite interface 'VopMetaData'
- Add parameter 'metadata' to VopReadyNotification

This way elements can handle their logic themselves without having to
rely on outside utility classes.

Also restructure files in common in a more logical way.

elementModels are described in the unitDefinition
elementCodes are saved in the unitState

Their values are mapped by the ElementModelElementCodeMappingService

- add unit-definition-menu module
- add verona module and move verona services and verona interfaces to it
  to make them available in different modules
- move the distinction of different page types to app component to make
  them available for unitDefinitionMenu component