Implement Get-PveApiToken, New-PveApiToken, and Remove-PveApiToken to
enable automated token management without manual Proxmox VE UI interaction.
Adds PveApiToken model, UserService methods for the token endpoints, and
31 Pester unit tests covering parameters, ShouldProcess, and no-session behaviour.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>