C# analyzer and formatting

[externl]

• Add StyleCop
• Format C# code
• Fix many lints and recommendations

Still various things to fix:

• Setting <AnalysisMode>All</AnalysisMode> causes many warnings
• various dotnet format warnings:

  Msbuild failed when processing the file '/Users/joe/Developer/zeroc-ice/ice-demos/csharp/Ice/callback/msbuild/client/client.csproj' with message: /Users/joe/.nuget/packages/zeroc.icebuilder.msbuild/5.0.9/build/zeroc.icebuilder.msbuild.csharp.targets: (53, 9): Ice Installation invalid or not detected. Invalid IceToolsPath setting `'
  ...
  Unable to fix SA1600. Code fix SettingsFileCodeFixProvider doesn't support Fix All in Solution.
  Unable to fix SA1600. Code fix InheritdocCodeFixProvider didn't return a Fix All action.

I tried to add dotnet format as a separate workflow but it failed to restore packages.

Run dotnet format --verify-no-changes "csharp/C# NET demos.sln"
Unhandled exception: System.Exception: Restore operation failed.
   at Microsoft.CodeAnalysis.Tools.CodeFormatter.OpenMSBuildWorkspaceAsync(String solutionOrProjectPath, WorkspaceType workspaceType, Boolean noRestore, Boolean requiresSemantics, String binaryLogPath, Boolean logWorkspaceWarnings, ILogger logger, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Tools.CodeFormatter.FormatWorkspaceAsync(FormatOptions formatOptions, ILogger logger, CancellationToken cancellationToken, String binaryLogPath)
   at Microsoft.CodeAnalysis.Tools.FormatCommandCommon.FormatAsync(FormatOptions formatOptions, ILogger`1 logger, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Tools.Commands.RootFormatCommand.FormatCommandDefaultHandler.InvokeAsync(ParseResult parseResult, CancellationToken cancellationToken)
   at System.CommandLine.Invocation.InvocationPipeline.InvokeAsync(ParseResult parseResult, CancellationToken cancellationToken)
Error: Process completed with exit code 1.

[pepone]

Run dotnet format --verify-no-changes "csharp/C# NET demos.sln"
Unhandled exception: System.Exception: Restore operation failed.

Probably because we didn't install the 3.8.0-alpha package, and it cannot be found in any of the default repositories.