Fix internal package version detection for project templates

[MackinnonBuck]

Summary

Fixes an issue where project templates would sometimes reference nonexistent versions of packages defined internally within the dotnet/extensions repo.

Fixes #6604

Description

This fix works by executing a target to directly extract the package version from each internal project referenced by the project templates. This enables us to avoid having to "guess" the version of internal packages via the $(Version) property, which may differ from project to project.

Microsoft Reviewers: Open in CodeFlow

[Copilot]

Pull Request Overview

This PR fixes an issue where project templates would sometimes reference nonexistent versions of packages defined internally within the dotnet/extensions repo. The fix replaces static version property references with a dynamic system that extracts package versions directly from internal project files.

Key changes include:

• Replaces manual package version mapping with automated extraction from project files
• Updates template variable names to be more specific (e.g., MicrosoftExtensionsAI_Preview → MicrosoftExtensionsAIOpenAI)
• Removes conditional logic for "just-built packages" detection

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
Directory.Build.targets.in	Removes conditional logic for detecting just-built packages
ChatWithCustomData-CSharp.Web.csproj.in	Updates package reference variable names to use new specific naming convention
GeneratedContent.targets	Replaces static package version properties with dynamic extraction system
GenerateTemplateContent.csproj	Adds MSBuild target to compute package versions from referenced projects
Packaging.targets	Adds helper target to extract package version information from projects

[jeffhandley]

I appreciate how surgical the changes are for consuming the versions in this new way.