Add CI package pipeline for building and publishing NuGet packages

[paulmedynski]

This is ready for review, but is based on PR #4300. It can't merge until that PR merges and I switch this PR to target main.

Adds a new top-level pipeline at eng/pipelines/ci/package/sqlclient-package.yml that:

• Runs on pushes to GitHub main and ADO internal/main branches (batched)
• Runs nightly at 00:00 UTC on those same branches
• Cleans the packages/ directory before building
• Uses build.proj Pack target with ReferenceType=Package
• On internal builds, downloads the signing key and strong-name signs assemblies
• Publishes all produced .nupkg/.snupkg files as a pipeline artifact

Tested ADO.Net project runs here:

• Linux: https://dev.azure.com/SqlClientDrivers/ADO.Net/_build/results?buildId=152354&view=results
• Windows: https://dev.azure.com/SqlClientDrivers/ADO.Net/_build/results?buildId=152348&view=results
• All pipeline parameters were tested between these 2 runs.

We can't test Public project runs until this merges, because we can only create new pipelines based on GitHub for YAML files on main.

[Copilot]

Pull request overview

Adds a new CI pipeline that builds and publishes NuGet packages via build.proj in ReferenceType=Package mode, alongside a broader refactor to make package-mode builds self-sustaining: version flow is unified through import-guarded Versions.props files imported early by Directory.Packages.props, all Pack* targets now mirror their output into the local packages/ feed and gain DependsOn chains so dependent packages restore against freshly built nupkgs, and many test/csproj files now switch between ProjectReference and PackageReference for Microsoft.SqlServer.Server based on ReferenceType. A new signed test category gates UDT tests that require a strong-name-signed Microsoft.SqlServer.Server.

Changes:

• New pipeline eng/pipelines/ci/package/sqlclient-package.yml (push to main/internal/main, nightly, optional strong-name signing on internal builds).
• build.proj and Directory.Packages.props overhaul: package-mode DependsOn/Pack mirroring, central SqlServerPackageVersion token wiring, category!=signed filter for unsigned builds.
• Threading of sqlServerArtifactsName/sqlServerPackageVersion through existing CI templates, and reference-mode switching for Microsoft.SqlServer.Server across csprojs (including nuspec token $SqlServerPackageVersion$).

Reviewed changes

Copilot reviewed 1 out of 1 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
eng/pipelines/ci/package/sqlclient-package.yml	New CI pipeline that packs all packages and publishes Packages artifact.
build.proj	Adds package-mode DependsOn chains, output mirroring to packages/, category!=signed filter, and PackageVersionSqlServer threading.
Directory.Packages.props	Imports all Versions.props in Package mode to centrally manage sibling package versions.
doc/Directory.Packages.props, doc/samples/Microsoft.Data.SqlClient.Samples.csproj	Pin and reorganize Microsoft.SqlServer.Server package usage.
src/Directory.Build.props	Comment clarifying FileVersionBuildNumber ordering relative to Directory.Packages.props.
src/**/Versions.props (×6)	Add per-product import-guard property to prevent double evaluation.
src/**/*.csproj (Logging, Abstractions, Azure, AKV, SqlServer, SqlClient src/ref/notsupported)	Conditional Versions.props import using the new guard; SqlClient ref/notsupported gain SqlServer reference; nuspec token updated.
src/Microsoft.Data.SqlClient/src/Microsoft.Data.SqlClient.csproj	Adds SqlServer version import, trim, validation error, and nuspec token replacement.
src/Microsoft.Data.SqlClient/src/Microsoft.Data.SqlClient.nuspec	Replaces hard-coded 1.0.0 with $SqlServerPackageVersion$ token.
src/Microsoft.Data.SqlClient/tests/UnitTests/...csproj	Adds ValidateReferenceType target and project reference to Microsoft.SqlServer.Server.
src/Microsoft.Data.SqlClient/tests/ManualTests/...csproj	Reference-mode switching for Microsoft.SqlServer.Server (top-level and UDT projects).
src/Microsoft.Data.SqlClient/tests/Common/Microsoft.Data.SqlClient.TestCommon.csproj	Enables ImplicitUsings.
src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/UdtTest/SqlServerTypesTest.cs, FunctionalTests/SqlDataRecordTest.cs	Adds [Trait("Category", "signed")] on NETFRAMEWORK for UDT tests requiring signed SqlServer assembly.
eng/pipelines/**/*.yml (ci-core, build-sqlclient/azure stages, ci-run-tests stage/job, ci-build-nugets, ci-project-build, run-all-tests, test-azure-package job)	Thread new sqlServerArtifactsName/sqlServerPackageVersion parameter and download the SqlServer artifact for package-mode test/build flows.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
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Additional details and impacted files

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.