patch https://api.fireblocks.io/v1/key_link/signing_keys//agent_user_id
Can modify existing signing key id if the key is not enabled. The change done in background and will be visible once applied. If key is already enabled (after proof of ownership) the user cannot be changed.
Please note that this endpoint is available only for Key Link enabled workspaces.
Endpoint Permission: Admin and Non-Signing Admin.