Capture App does not upload the signed message to backend

[shc261392]

Description

The message content signed in App (serialized signedTargets) is different from the string uploaded to DIA backend as meta field. Currently, the App never provide the correct signed message to backend in any way.

In order to verify the signature using the information stored on the backend, the App must have a way to upload the signed message to backend for all assets created from the App.

Environment

• Version:All

Limitation

Because the generated key pair is destroyed when the App is deleted, if the user ever deletes the App even once, we have no way to remake signatures with the original key pair for the assets created before the user deletes the App. (It's meaningless anyway since the user also lost their wallet when deleting the App)

We could use the new key pair to generate a completely new signature though.