[Windows] Add dependency-resolution preflight for downstream builds

[alex-harvey-z3q]

Description

Adds an opt-in, non-installing Windows dependency-resolution preflight for downstream consumers to run from the exact revision they are about to build, before starting Packer.

-Image is required so that the template and toolset being checked always match the intended build. Supported targets are:

• Windows2022
• Windows2025
• Windows2025VS2026
• Windows11Arm64
• Windows11VS2026Arm64

The preflight:

• parses all Windows PowerShell scripts and validates the selected template’s local references;
• resolves configured toolcache versions from the selected toolset’s manifests;
• resolves every configured Chocolatey package, including each explicit package version, from the Chocolatey community feed;
• resolves every configured PowerShell Gallery module, including each explicit module version, from the Gallery’s NuGet V2 endpoint;
• checks selected GitHub release asset patterns, using GITHUB_TOKEN when supplied to avoid API-rate-limit false failures;
• validates Visual Studio Marketplace metadata and the existing Microsoft VSIX download overrides; and
• retries transient endpoint failures with bounded retries and clear final errors.

It does not create Azure resources, provision a VM, download installer payloads, or mutate the build machine. -SkipNetwork runs the static checks only.

The accompanying unit suite uses mocked endpoint responses and runs in the existing fast PowerShell-test workflow when the preflight changes.

Related issue:

• Refs Provide a fast Windows dependency-resolution preflight for downstream image builds #14564

Check list

• Related issue / work item is attached
• Tests are written (if applicable)
• Documentation is updated (if applicable)
• Changes are tested and related VM images are successfully generated

Validation

• Invoke-Pester -Output Detailed images/windows/scripts/preflight/tests (15 passed)
• Static preflight for all five supported -Image values
• Live Chocolatey probes for Bicep and toolset-pinned cmake.install 3.31.6
• Live PowerShell Gallery probe for toolset-pinned Pester 5.9.0
• PowerShell parser and whitespace checks