[StaticWebAssets] Improve Up to date check logic

[javiercn]

• Implements specific targets for the up-to-date check for static web assets.

Validated the scenarios manually, since this functionality is tied to VS:

• Add a file:
  • Build: Project is not up to date (build).
  • Build: Project becomes up to date (nothing to do).
• Update a file:
  • Build: Project is not up to date (build).
  • Build: Project becomes up to date (nothing to do).
• Remove a file:
  • Build: Project is not up to date (build).
  • Build: Project becomes up to date (nothing to do).
• Add a file on a dependent project:
  • Build: Project is not up to date (build).
  • Build: Project becomes up to date (nothing to do).
• Update a file on a dependent project:
  • Build: Project is not up to date (build).
  • Build: Project becomes up to date (nothing to do).
• Remove a file on a dependent project:
  • Build: Project is not up to date (build).
  • Build: Project becomes up to date (nothing to do).

[javiercn]

/backport to release/9.0.1xx

[github-actions]

Started backporting to release/9.0.1xx: https://github.com/dotnet/sdk/actions/runs/10644272725