Enable Remote Command Execution for Registered SSH Keys

Problem

When SSH Keys are registered from CSP resources, they lack critical authentication information (username and privateKey), preventing remote command execution on associated VMs. Users cannot execute commands via MapUI or API calls on registered VMs.

Root Cause

1. Registered SSH Keys missing required fields: SSH Keys registered from CSP console don't include username or privateKey in CB-Tumblebug database
2. PUT API had a bug: The PUT API did not function as originally intended; instead of updating existing fields, it mistakenly created a new object.

Solution

1. Added dedicated complement API

Created a new endpoint specifically for enabling remote command execution:

PUT /ns/{nsId}/resources/sshKey/{sshKeyId}/complement

This API only requires the essential fields needed for SSH authentication:

type SshKeyComplementReq struct {
    Username   string `json:"username"`    // Required: SSH username
    PrivateKey string `json:"privateKey"`  // Required: SSH private key
}

2. Maintained general update API

The existing PUT API continues to support SSH Key updates:

PUT /ns/{nsId}/resources/sshKey/{sshKeyId}

type SshKeyUpdateReq struct {
    Description      string `json:"description"`
    Fingerprint      string `json:"fingerprint"`
    Username         string `json:"username"`
    VerifiedUsername string `json:"verifiedUsername"`
    PublicKey        string `json:"publicKey"`
    PrivateKey       string `json:"privateKey"`
}

Benefits

1. Enables remote command execution: Registered VMs can now execute commands after Complementing a SSH Key info
2. Clear API semantics: Dedicated /complement endpoint makes the intent explicit
3. Minimal required fields: Only username and privateKey needed for activation