Bug where attributes set in Tree are not displayed in the dashboard

[hackerwins]

Description:

There is a bug where attributes set in Tree are not displayed in the dashboard.

Dashboard retrieves detailed information about a document by calling the GetDocument API from the server. It is suspected that attributes might be missing in the snapshot generated by the server.

Dashboard:

dashboard/src/features/documents/DocumentDetail.tsx

Lines 36 to 39 in d32345e

	getDocumentAsync({
	projectName,
	documentKey,
	}),

Server: https://github.com/yorkie-team/yorkie/blob/525cacf2747f53187e41fd495e41f1b26e0a5d4e/server/rpc/admin_server.go#L209-L233

Why:

[krapie]

I think this is because codes for marshalling tree attributes are missing in Marshal() in crdt.Tree.

https://github.com/yorkie-team/yorkie/blob/525cacf2747f53187e41fd495e41f1b26e0a5d4e/pkg/document/crdt/tree.go#L286

(And GetDocummentSummary() uses Marshal() for creating snapshot).