FirewallService.GetGroupRules/CreateGroupRule/UpdateGroupRule/RemoveGroupRule
already existed with zero callers. Get/New/Set/Remove-PveFirewallRule gain a
Group value in their -Level ValidateSet and a -Group parameter, required and
validated the same way Node/VmId are validated for the other levels, and
dispatch to those service methods instead of the generic BuildBasePath-driven
ones. No cmdlet in this area built its own client, so unlike the other #126
areas there is no inline request to strip.
Co-authored-by: goodolclint-claude[bot] <323206664+goodolclint-claude[bot]@users.noreply.github.com>