Resolve "Update gRPC abstraction API with missing calls and refactoring"

Description

Complete:

• User
• Role
• Pnd
  • To dicuss: CreatePnd call, uses CreatePndList, should name of the API call be the same even if we only gice the option to add one? Can we make it optional to add multiple in the API call too?
  • Maybe do only one call where a list of one or many is provided?
• Plugin

• Maybe move GetPluginSchemaTree from MNE to Plugin?

• MNE

• For creation: Maybe do only one call where a list of one or many is provided?
• Need to discuss Update function again!

• Auth

Missing for now. Maybe implement?:

• ConfigurationManagement
• Route (Not implemented because this will probably get reworked)
• Topology (Not implemented because this will probably get reworked)
• App

Related to #359

controller/api/managedNetworkElement.go

@@ -50,6 +50,23 @@ func AddNetworkElement(ctx context.Context, addr, mneName, mneUUID string, opt *
 	return client.AddList(ctx, req)
 }
 
+// AddNetworkElementList adds all the network elements to the controller. The name of each network element is optional.
+// If no name is provided a name will be generated upon network element creation.
+func AddNetworkElementList(ctx context.Context, addr, pid string, mneList []*mnepb.SetMne) (*mnepb.AddListResponse, error) {
+	client, err := nbi.NetworkElementClient(addr, dialOptions...)
+	if err != nil {
+		return nil, err
+	}
+
+	req := &mnepb.AddListRequest{
+		Timestamp: time.Now().UnixNano(),
+		Mne:       mneList,
+		Pid:       pid,
+	}
+
+	return client.AddList(ctx, req)
+}
+
 // GetNetworkElement requests one network element belonging to a given
 // PrincipalNetworkDomain from the controller. If no network element identifier
 // is provided, an error is thrown.
@@ -72,6 +89,21 @@ func GetNetworkElement(ctx context.Context, addr, pid string, mneid string) (*mn
 	return client.Get(ctx, req)
 }
 
+// GetNetworkElements requests all available network elements related to one PND.
+func GetNetworkElements(ctx context.Context, addr, pid string) (*mnepb.GetAllResponse, error) {
+	client, err := nbi.NetworkElementClient(addr, dialOptions...)
+	if err != nil {
+		return nil, err
+	}
+
+	req := &mnepb.GetAllRequest{
+		Timestamp: time.Now().UnixNano(),
+		Pid:       pid,
+	}
+
+	return client.GetAll(ctx, req)
+}
+
 // GetPluginSchemaTree gets the schema tree for a plugin.
 func GetPluginSchemaTree(ctx context.Context, addr string, pluginID uuid.UUID) (map[string]*yang.Entry, error) {
 	pluginClient, err := nbi.PluginClient(addr, dialOptions...)