nfs: expose dcache version in EXCHANGE_ID operation

Motivation:
NFSv4.1 spec allows client and server to exchange their implementation
identities, which can be useful during debugging. Up to now, dCache was
exposing the implementation implementation id of  nfs4j, which is not
quite correct.

Modification:
inject dcache name and version into servers implementation id.

Result:
more info during debugging.

Acked-by: Lea Morschel
Acked-by: Albert Rossi
Target: master
Require-book: no
Require-notes: yes

modules/dcache-nfs/src/main/java/org/dcache/chimera/nfsv41/door/NFSv41Door.java

@@ -177,6 +177,7 @@
 import org.dcache.util.RedirectedTransfer;
 import org.dcache.util.Transfer;
 import org.dcache.util.TransferRetryPolicy;
+import org.dcache.util.Version;
 import org.dcache.vehicles.DoorValidateMoverMessage;
 import org.dcache.vehicles.FileAttributes;
 import org.slf4j.Logger;
@@ -485,6 +486,8 @@ public void init() throws Exception {
                           .withExportTable(_exportFile)
                           .withVfs(_vfs)
                           .withOperationExecutor(_executor)
+                          .withImplementationName("dcache-" + Version.of(this.getClass()).getBuild())
+                          .withImplementationDate(Instant.parse(Version.of(this.getClass()).getBuildTime()))
                           .build();
 
                     oncRpcSvcBuilder.withRpcService(