drive: support metadata setting and mapping on server side Move,Copy

Before this change the backend would not run the metadata mapper and
it would ignore metadata set when doing server side moves or copies.

backend/drive/drive.go

@@ -2791,6 +2791,12 @@ func (f *Fs) Copy(ctx context.Context, src fs.Object, remote string) (fs.Object,
 		createInfo.Description = ""
 	}
 
+	// Adjust metadata if required
+	updateMetadata, err := f.fetchAndUpdateMetadata(ctx, src, fs.MetadataAsOpenOptions(ctx), createInfo, false)
+	if err != nil {
+		return nil, err
+	}
+
 	// get the ID of the thing to copy
 	// copy the contents if CopyShortcutContent
 	// else copy the shortcut only
@@ -2804,7 +2810,7 @@ func (f *Fs) Copy(ctx context.Context, src fs.Object, remote string) (fs.Object,
 	var info *drive.File
 	err = f.pacer.Call(func() (bool, error) {
 		copy := f.svc.Files.Copy(id, createInfo).
-			Fields(partialFields).
+			Fields(f.getFileFields(ctx)).
 			SupportsAllDrives(true).
 			KeepRevisionForever(f.opt.KeepRevisionForever)
 		srcObj.addResourceKey(copy.Header())
@@ -2840,6 +2846,11 @@ func (f *Fs) Copy(ctx context.Context, src fs.Object, remote string) (fs.Object,
 			fs.Errorf(existingObject, "Failed to remove existing object after copy: %v", err)
 		}
 	}
+	// Finalise metadata
+	err = updateMetadata(ctx, info)
+	if err != nil {
+		return nil, err
+	}
 	return newObject, nil
 }
 
@@ -3013,13 +3024,19 @@ func (f *Fs) Move(ctx context.Context, src fs.Object, remote string) (fs.Object,
 	dstParents := strings.Join(dstInfo.Parents, ",")
 	dstInfo.Parents = nil
 
+	// Adjust metadata if required
+	updateMetadata, err := f.fetchAndUpdateMetadata(ctx, src, fs.MetadataAsOpenOptions(ctx), dstInfo, true)
+	if err != nil {
+		return nil, err
+	}
+
 	// Do the move
 	var info *drive.File
 	err = f.pacer.Call(func() (bool, error) {
 		info, err = f.svc.Files.Update(shortcutID(srcObj.id), dstInfo).
 			RemoveParents(srcParentID).
 			AddParents(dstParents).
-			Fields(partialFields).
+			Fields(f.getFileFields(ctx)).
 			SupportsAllDrives(true).
 			Context(ctx).Do()
 		return f.shouldRetry(ctx, err)
@@ -3028,6 +3045,11 @@ func (f *Fs) Move(ctx context.Context, src fs.Object, remote string) (fs.Object,
 		return nil, err
 	}
 
+	// Finalise metadata
+	err = updateMetadata(ctx, info)
+	if err != nil {
+		return nil, err
+	}
 	return f.newObjectWithInfo(ctx, remote, info)
 }