MarbleRun unauthenticated recovery allows Coordinator impersonation

Summary

### Impact

During recovery, a Coordinator only verifies that a given recovery key decrypts the sealed state, not if this key was provided by a party with access to one of the recovery keys defined in the manifest. This allows an attacker to manually craft a sealed state using their own recovery keys, and a manifest that does not match the rest of the state.

If network traffic is redirected from the legitimate coordinator to the attacker's Coordinator, a remote party is susceptible to impersonation if they verify the Coordinator without comparing the root certificate of the Coordinator against a trusted reference.

Under these circumstances, an attacker can trick a remote party into trusting the malicious Coordinator by presenting a manifest that does not match the actual state of the deployment.

This issue does **not** affect the following:

* secrets and state of the legitimate Coordinator instances * integrity of workloads * certificates chaining back to the legitimate Coordinator root certificate

### Patches

The issue has been patched in [`v1.7.0`](https://github.com/edgelesssys/marblerun/releases/tag/v1.7.0).

### Workarounds

Connections that purely authenticate based on a known Coordinator's root certificate, e.g. the one retrieved when using the `marblerun manifest set` CLI command, are not affected.