Feature target metadata ui (#765)

* add metadata tab and popup to target UI

Signed-off-by: Stefan Klotz <stefan.klotz@bosch-si.com>

* send event to update UI

Signed-off-by: Stefan Klotz <stefan.klotz@bosch-si.com>

* send event on target meta data delete and update

Signed-off-by: Stefan Klotz <stefan.klotz@bosch-si.com>

* display selected element name in details layout and metadata popup of UI

Signed-off-by: Stefan Klotz <stefan.klotz@bosch-si.com>

* add comments to explain manual event publishing

Signed-off-by: Stefan Klotz <stefan.klotz@bosch-si.com>

* remove option to hide metadata button in details layout

Signed-off-by: Stefan Klotz <stefan.klotz@bosch-si.com>

* fix typos and refactor

Signed-off-by: Stefan Klotz <stefan.klotz@bosch-si.com>

* fix typos

Signed-off-by: Stefan Klotz <stefan.klotz@bosch-si.com>

* fix wrong method call

Signed-off-by: Stefan Klotz <stefan.klotz@bosch-si.com>

hawkbit-rest/hawkbit-mgmt-resource/src/main/java/org/eclipse/hawkbit/mgmt/rest/resource/MgmtTargetResource.java

@@ -388,7 +388,7 @@ public class MgmtTargetResource implements MgmtTargetRestApi {
     @Override
     public ResponseEntity<MgmtMetadata> updateMetadata(@PathVariable("targetId") final String targetId,
             @PathVariable("metadataKey") final String metadataKey, @RequestBody final MgmtMetadataBodyPut metadata) {
-        final TargetMetadata updated = targetManagement.updateMetaData(targetId,
+        final TargetMetadata updated = targetManagement.updateMetadata(targetId,
                 entityFactory.generateTargetMetadata(metadataKey, metadata.getValue()));
         return ResponseEntity.ok(MgmtTargetMapper.toResponseTargetMetadata(updated));
     }