<auto-generated/> is not respected by CS1591

[adamsitnik]

While working on microsoft/semantic-kernel#11155 I've run into a bug: <auto-generated/> is not respected by CS1591.

The issue is known to the compiler team: dotnet/roslyn#41171

Most of the users workaround it by adding a dedicated pragma warning disable like here in dotnet/runtime:

https://github.com/dotnet/runtime/blob/d23f2514eceb39c7bb85bf392f3742c301290dac/src/libraries/Microsoft.Extensions.Options/tests/SourceGeneration.Unit.Tests/Baselines/UsingInterfaceAsPropertyTypeForLengthAttributesTests.netcore.g.cs#L2-L5

I decided to simply add the XML doc comments (which is nice anyway as users are supposed to consume it). This is what S.T.J did in dotnet/runtime#72761 as well

Standalone repro:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Library</OutputType>
    <TargetFramework>net8.0</TargetFramework>
    <RunAnalyzersDuringBuild>true</RunAnalyzersDuringBuild>
    <EnableNETAnalyzers>true</EnableNETAnalyzers>
    <AnalysisMode>AllEnabledByDefault</AnalysisMode>
    <AnalysisLevel>latest</AnalysisLevel>
    <NoWarn></NoWarn> <!-- Ensure CS1591 is not suppressed -->
    <WarningsAsErrors>CS1591</WarningsAsErrors> <!-- Treat missing XML docs as warnings or errors -->
    <GenerateDocumentationFile>true</GenerateDocumentationFile> <!-- Generate XML documentation -->
  </PropertyGroup>
</Project>

// <auto-generated/>

using System.Data.Common;

namespace AutoGeneratedWarning
{
    public static class SqliteVectorExtensions
    {
        public static void LoadVector(this DbConnection connection)
        {
            _ = connection;
        }
    }
}