Add OAT compatibility with Opencast Version 13

[oellers]

Due to some changes in OC 13 regarding persistence (see OC PR 3903), the dependencies (org.opencastproject.util.persistence.*) are missing and the build will fail.

The backend of the OAT should be rewritten to reflect the changes.

Workaround (not recommended):
Add removed dependencies to OAT, e.g.

opencast-backend/annotation-impl/src/main/java/org/opencastproject/util/persistence/PersistenceEnv.java 
opencast-backend/annotation-impl/src/main/java/org/opencastproject/util/persistence/PersistenceEnv2.java
opencast-backend/annotation-impl/src/main/java/org/opencastproject/util/persistence/PersistenceEnvs.java
opencast-backend/annotation-impl/src/main/java/org/opencastproject/util/persistence/PersistenceUtil.java
opencast-backend/annotation-impl/src/main/java/org/opencastproject/util/persistence/Queries.java
opencast-backend/annotation-impl/src/main/java/org/opencastproject/util/persistencefn/PersistenceEnv.java
opencast-backend/annotation-impl/src/main/java/org/opencastproject/util/persistencefn/PersistenceEnvs.java
opencast-backend/annotation-impl/src/main/java/org/opencastproject/util/persistencefn/PersistenceUtil.java
opencast-backend/annotation-impl/src/main/java/org/opencastproject/util/persistencefn/Queries.java