fix: skip Point-and-Print relaxation for existing connections

[man612]

Summary

Prevent temporary Point and Print compatibility from lowering driver-installation protection when the requested shared printer is already connected.

Bug reproduced before this fix

With the target UNC already present in printer inventory, the action still:

• created an emergency restore snapshot
• lowered RestrictDriverInstallationToAdministrators
• called Add-Printer
• restored the registry afterward

That meant security protection was relaxed unnecessarily even though no connection work was required.

Fix

• validate the UNC as before
• immediately check printer inventory for the exact target UNC
• if already connected, return before:
  • RISK confirmation
  • strict registry read
  • restore snapshot creation
  • Point and Print security relaxation
  • Add-Printer / PrintUI
  • rollback logic
• explain to the user that the printer is already connected and protection was left unchanged

Regression coverage

tests/PointAndPrintSafetySmoke.ps1 now verifies that an already-connected target:

• preserves the existing Restore pointer
• prompts only for the UNC, not RISK
• creates no snapshot
• performs no registry read/write
• performs no Add-Printer call
• performs no rollback call

Existing success, connection failure, no-op Add-Printer, and rollback failure scenarios remain covered.

Local Windows PowerShell 5.1 verification

• direct AST parse: pass
• PSScriptAnalyzer 1.25.0: 0 actionable diagnostics
• PointAndPrintSafetySmoke: pass
• LegacyNoOpSmoke: pass
• RepairOutcomeSmoke: pass
• RepairPostconditionSmoke: pass
• RestoreOutcomeSmoke: pass
• RestoreActionContractSmoke: pass
• ServiceRestoreScopeSmoke: pass
• SnapshotScopeSmoke: pass
• RestoreSafetySmoke: pass
• Validate.ps1: pass

The connection capability is unchanged; unnecessary security relaxation is removed.