Implement what-if functionality for Windows service operation

[Gijsreyn]

PR Summary

Adds what-if support for Microsoft.Windows/Service set operations so the resource can return projected state and _metadata.whatIf details without changing the service.

PR Context

Fixes #1506

[Copilot]

Pull request overview

Adds native what-if support for the Microsoft.Windows/Service command resource so dsc resource set --what-if can return a projected afterState plus _metadata.whatIf entries without changing the actual service.

Changes:

• Introduces _metadata.whatIf modeling on the WindowsService type for what-if projections.
• Extends the set operation plumbing to parse a what-if flag and return projected state/messages (including delete projections when _exist:false).
• Adds Pester coverage for what-if projections and new localized what-if strings.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
resources/windows_service/tests/windows_service_set.tests.ps1	Adds Pester tests validating projected state and _metadata.whatIf for what-if set/delete scenarios.
resources/windows_service/src/types.rs	Adds _metadata / Metadata types to the resource’s JSON model.
resources/windows_service/src/service.rs	Implements what-if projection logic for set and delete operations; updates set_service signature.
resources/windows_service/src/main.rs	Parses --what-if and routes set requests accordingly (including delete projection).
resources/windows_service/locales/en-us.toml	Adds user-facing what-if messages and updates usage text.