feat(cli):migrate cloud network private vrack to API v2

[duboolivier]

Description

Migrates the cloud network private vrack network and subnet commands from the v1
region-based API to the Cloud API v2 (/v2/publicCloud/project/{id}/network...).

• network (vRack private): list, get, create, delete, edit (new, PUT)
• subnet: list, get, create, delete, edit (new, PUT); subnet inherits the parent network's region when --region is omitted
• Adds --wait (async provisioning) via waitForCloudResourceReady
• cloud network public and cloud network gateway are left on v1 (no v2 equivalent yet)

Tested end-to-end against the real v2 API (network + subnet: create → get → edit → list → delete).

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (improvement of existing commands)
• Breaking change (fix or feature that can break a current behavior)
• Documentation update

Checklist:

• My code follows the style guidelines of this project
• I have commented my code
• I ran go mod tidy
• I have added tests that prove my fix is effective or that my feature works