[MSBUILD SDK] Error out build if incompatible SDK is present

[jviau]

Issue describing the changes in this PR

resolves #issue_for_this_pr

Pull request checklist

• My changes do not require documentation changes
  • Otherwise: Documentation issue linked to PR
• My changes should not be added to the release notes for the next release
  • Otherwise: I've added my notes to release_notes.md
• My changes do not need to be backported to a previous version
  • Otherwise: Backport tracked by issue/PR #issue_or_pr
• I have added all required tests (Unit tests, E2E tests)

Additional information

This PR expands a build/restore target to also error out if Microsoft.Azure.Functions.Worker.Sdk is being used in the new MSBuild sdk.

[Copilot]

Pull request overview

This PR expands the SDK validation to detect and error out when incompatible SDK packages are referenced in a project. The validation is generalized from checking only the legacy in-proc SDK to checking both Microsoft.NET.Sdk.Functions and Microsoft.Azure.Functions.Worker.Sdk.

Changes:

• Renamed the validation target and error message to reflect that it now checks for multiple incompatible SDKs, not just the legacy one
• Updated the MSBuild target to check PackageReference items instead of a build property
• Added test coverage for both incompatible SDK packages during restore

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/Azure.Functions.Sdk/Targets/Azure.Functions.Sdk.targets	Renamed target from _FunctionAppValidation to _CheckForConflictingFunctionSdk, updated to check PackageReference items for both incompatible SDKs
src/Azure.Functions.Sdk/Strings.resx	Renamed error message resource and updated text to be parameterized for different package names
src/Azure.Functions.Sdk/LogMessage.cs	Renamed constant from Error_UsingLegacyFunctionsSdk to Error_UsingIncompatibleSdk and updated FromId mapping
test/Azure.Functions.Sdk.Tests/Integration/SdkEndToEndTests.Restore.cs	Added parameterized test to verify both incompatible SDKs are detected during restore

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