Platform-aware Install-PSResource: filter runtimes by RID, libs by TFM

[jshigetomi]

PR Summary

Adds automatic RID (Runtime Identifier) and TFM (Target Framework Moniker) filtering during package extraction, plus two new parameters (-RuntimeIdentifier, -TargetFramework) for explicit cross-platform/cross-framework deployment.

---

Design Decisions for Review

1. Root-level RID folders, not NuGet runtimes/ convention

PowerShell modules use win-x64/, linux-x64/ at the package root for native assets, not the standard NuGet runtimes/{rid}/native/ layout. Filtering targets this PS-ecosystem convention.

2. Merge semantics on re-install with explicit overrides

• No override specified + already installed → warn and skip (unchanged behavior)
• Explicit -TargetFramework or -RuntimeIdentifier + already installed → merge new content into existing version directory without overwriting files
• -Reinstall + override → full replace (clean filtered install)

This enables incremental multi-target builds:

Install-PSResource -Name MyModule                             # gets net8.0
Install-PSResource -Name MyModule -TargetFramework 'net472'   # merges net472 into same dir

3. Singular TFM selection — no fallback extraction

NuGet.Frameworks.FrameworkReducer picks the single best-match TFM from lib/. Only that TFM's assemblies are extracted — no fallback that extracts multiple TFMs. This prevents accidental cross-lineage mixing but means users must explicitly merge if they need both.

4. Cross-lineage warning

When the selected TFM is .NETCoreApp but the package also has net472 (or vice versa), a non-fatal warning tells the user how to add the other lineage:

WARNING: This package contains assemblies for net472 which were not installed
because the current runtime selected net8.0. If you also use this module on
Windows PowerShell 5.1, run: Install-PSResource -Name <ModuleName> -TargetFramework 'net472'

---

PR Context

Platform aware installation was brought up in issue: #794.

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Make sure all .h, .cpp, .cs, .ps1 and .psm1 files have the correct copyright header
• This PR is ready to merge and is not Work in Progress.
  • If the PR is work in progress, please add the prefix WIP: or [ WIP ] to the beginning of the title (the WIP bot will keep its status check at Pending while the prefix is present) and remove the prefix when the PR is ready.
• Breaking changes
  • None
  • OR
  • Documentation needed
    • Issue filed:
• User-facing changes
  • Not Applicable
  • OR
  • Documentation needed
    • Issue filed: Documentation Request: Platform-Aware Installation for Install-PSResource MicrosoftDocs/PowerShell-Docs#12891
• Testing - New and feature
  • N/A or can only be tested interactively
  • OR
  • Make sure you've added a new test if existing tests do not effectively test the code changed
• Tooling
  • I have considered the user experience from a tooling perspective and don't believe tooling will be impacted.
  • OR
  • I have considered the user experience from a tooling perspective and enumerated concerns in the summary.