#656

#605

#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

Change import paths of CommonModule files in editor and player

This removes all the classes and goes back to simple interfaces for
unit, pages etc and all elements. This makes creating them easier and
cleaner.
Things like specific needs when setting element properties and most
importantly compatibility handling is done by a special service module,
that knows all the elements and how to repair old their potentially
outdated definitions.

This reverts commit 93e62a4a.
Teststudio does not accept verona 4 specification data

see Verona Api

* Add `InputElementValue` as type when needed

* When elements receive the focusin event, their status is changed to
`TOUCHED`
* Replace `this.form.valueChanges` subscription with
`this.unitStateService.unitStateElementCodeChanged` subscription

* Value and status of all elements are saved
* Move some Methods and Properties from FormService to UnitStateService

* `UnitState.dataparts` has property `elementCodes` property, which
stores status, value and id for FormElement
* When building a unit, the stored value is assigned to the element
when it is initiated
* Removed `UnitState.dataparts.pages`
* Removed methods initPages and addStoredValues

* in eager mode a vopStateChangedNotification is still sent
* otherwise the last state is cached in the `VeronaPostService` and
can be retrieved from the host

* Define data version types data versions for `unitDefinition` and
`unitState` in meta tag of index.html
* Separate `MetaDataService` from `VeronaPostService`
* Extend `MetaDataService` to verify data versions of `unitDefinition` and
`unitState`

`PlayerStateComponent` encapsulates information about the status of the
player.

* Add verona interfaces to ensure type-safe communication with host
* To use the verona interfaces refactor the verona services