Thread-Safe implementation of the *InMemoryBackends

[aaronzi]

Currently, the implementation of the *InMemoryBackends is not handled thread-safe. This should be fixed.

Entrypoints

• basyx-java-server-sdk/basyx.submodelrepository/basyx.submodelrepository-backend-inmemory/src/main/java/org/eclipse/digitaltwin/basyx/submodelrepository/SubmodelInMemoryBackend.java at main · eclipse-basyx/basyx-java-server-sdk · GitHub

• basyx-java-server-sdk/basyx.aasrepository/basyx.aasrepository-backend-inmemory/src/main/java/org/eclipse/digitaltwin/basyx/aasrepository/backend/inmemory/AasInMemoryBackend.java at main · eclipse-basyx/basyx-java-server-sdk · GitHub