ISIS-939: simplified PersistenceMechanismInstallerAbstract and its subclasses, also PersistenceSessionFactoryDelegating, PersistenceSessionFactoryDelegate.

* Replaced PersistenceSessionFactoryDelegate#createPersistenceSession with #createObjectStore (other common functionality moved to PersistenceSessionFactoryDelegating).
* Don't pass ObjectAdapterFactory, AdapaterManagerSpi, OidGenerator into PersistenceSession; instead it can new these up (there is no variation in implementation nor state held in these components)
* Removed IsisObjectStoreLogger, IsisObjectStoreDelegating.
ISIS-939: more simplified of persistence sessions and object stores.

- deleted ObjectStoreSpi, just use ObjectStore (impl) directly;
- deleted AdapterManagerAbstract, not used
- deleted AdapterMapDelegator, not used
- for in-memory objectstore, renamed ObjectStorePersistedObjectsDefault (impl) to ObjectStorePersistedObjects (unextracted interface)
- renamed PersistenceSessionFactoryDelegate to ObjectStoreFactory
- renamed PersistenceSessionFactoryDelegating to PersistenceSessionFactory (unextracted interface)
- removed AdapterManagerSpi interface, just use AdapterManagerDefault directly instead.
- deleted AdpaterUtils, not used
ISIS-939: deleted the UpdateNotifier subcomponent.  Not used by any released code, and the same information (and better) is available in the IsisTransaction itself.
ISIS-939: simplified MessageBroker

- removed the defunct MessageBroker interface (in runtime)
- renamed MessageBrokerDefault to MessageBroker (unextract interface), now in metamodel
- removed #setApplicationError, since no longer used.
ISIS-939: deleted AdapterLifecycleTransitioner interface (performed no function).

Also: deleted unused/undocumented IsisServices service.
ISIS-939: simplifying PersistenceSession

- removing PersistenceSession#resolveField (introduce ResolveFieldUtil for scimpi to call), also from the *ObjectStore impls
- remove Persistor interface, instead PersistenceSession everywhere
- remove ToPersistObjectSet interface, instead PersistenceSession everywhere
- remove RecreatedPojoRemapper interface, instead PersistenceSession everywhere
- remove EnlistedObjectDirtying interface, instead PersistenceSession everywhere
- remove ObjectAdapterMemento#getTitleHint() and #captureTitleHintIfPossible()
- re-introduce MessageBroker's #getApplicationError and #setApplicationError
- remove ObjectAdapter#isTitleAvailable() and from PojoAdapter
- removed commented out lines in ResolveState
- simplify PersistenceSession (remove #mapRecreatedPojo, #remapRecreatedPojo)
- introduce PersistenceQueryFactory from PersistenceSession
- PersistenceSession creates IsisTransactionManager in its constructor
ISIS-939: clear the MessageBroker's applicationError field once read (functionality lost in previous refactorings).
ISIS-941: don't try to flush property changes from form for disabled properties.
ISIS-537: update to ToDoItem's layout to demonstrate labelAt facet.