fix(server): Fix unlocking before callbacks in ActivateSession
fix(server): Fix unlocking before callbacks in ActivateSession

jpfr/open62541,jpfr/open62541,StalderT/open62541,open62541/open62541,JGrothoff/open62541,StalderT/open62541,StalderT/open62541,JGrothoff/open62541,jpfr/open62541,open62541/open62541,open62541/open62541,jpfr/open62541,JGrothoff/open62541,JGrothoff/open62541,StalderT/open62541,open62541/open62541