[Logs] Add extension for registering OpenTelemetryLoggerProvider with ILoggingBuilder

[CodeBlanch]

Following up on #3454 (comment)

Changes

• Adds an extension for manually registering an OpenTelemetryLoggerProvider with an ILoggingBuilder. You don't really need this extension to do that, but I think it helps with discoverability and our documentation/examples to have it.

Details

Here is the use case I am thinking about.

The Serilog startup pattern configures the log pipeline before the host builder. That sort of prescribes that users will need to manually build their own OpenTelemetryLoggerProvider. What this new extension does is just smooth that out.

    public static int Main(string[] args)
    {
        OpenTelemetryLoggerProvider provider = new OpenTelemetryLoggerProvider(options =>
        {
            options.IncludeFormattedMessage = true;
            options.AddConsoleExporter();
        });

        Log.Logger = new LoggerConfiguration()
            .WriteTo.OpenTelemetry(provider, disposeProvider: true)
            .CreateLogger();

        try
        {
            Log.Information("Starting web host");
            CreateHostBuilder(args, provider).Build().Run();
            return 0;
        }
        catch (Exception ex)
        {
            Log.Fatal(ex, "Host terminated unexpectedly");
            return 1;
        }
        finally
        {
            Log.CloseAndFlush();
        }
    }

    public static IHostBuilder CreateHostBuilder(string[] args, OpenTelemetryLoggerProvider openTelemetryLoggerProvider) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureLogging(builder =>
                {
                    builder.AddOpenTelemetry(openTelemetryLoggerProvider, disposeProvider: false); // <- New extension used here
                })
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });

Public API

+ public static ILoggingBuilder AddOpenTelemetry(this ILoggingBuilder builder)
+ public static ILoggingBuilder AddOpenTelemetry(this ILoggingBuilder builder, Action<OpenTelemetryLoggerOptions>? configure)
+ public static ILoggingBuilder AddOpenTelemetry(this ILoggingBuilder builder, OpenTelemetryLoggerProvider openTelemetryLoggerProvider)
+ public static ILoggingBuilder AddOpenTelemetry(this ILoggingBuilder builder, OpenTelemetryLoggerProvider openTelemetryLoggerProvider, bool disposeProvider)
- public static ILoggingBuilder AddOpenTelemetry(this ILoggingBuilder builder, Action<OpenTelemetryLoggerOptions>? configure = null)

The reason that one method is being removed is I first tried this...

public static ILoggingBuilder AddOpenTelemetry(this ILoggingBuilder builder, Action<OpenTelemetryLoggerOptions>? configure = null)
public static ILoggingBuilder AddOpenTelemetry(this ILoggingBuilder builder, OpenTelemetryLoggerProvider openTelemetryLoggerProvider)

...which gave me the warning:

Symbol 'AddOpenTelemetry' violates the backcompat requirement: 'Public API with optional parameter(s) should have the most parameters amongst its public overloads'. See 'https://github.com/dotnet/roslyn/blob/master/docs/Adding%20Optional%20Parameters%20in%20Public%20API.md' for details.

The layout of the new methods fixes that. Checked with @tarekgh. New design should be mostly safe. If users were calling these methods with reflection and specifically checking the metadata for "optional" parameter, they would break. But I feel like that is a super edge case. Anyone just compiling should be fine.

TODOs

• Appropriate CHANGELOG.md updated for non-trivial changes
• Changes in public API reviewed
• Tests

[codecov]

Codecov Report

Merging #3489 (b7903b0) into main (f089ec7) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #3489   +/-   ##
=======================================
  Coverage   86.49%   86.49%           
=======================================
  Files         272      272           
  Lines        9931     9939    +8     
=======================================
+ Hits         8590     8597    +7     
- Misses       1341     1342    +1     

Impacted Files	Coverage Δ
...enTelemetry/Logs/OpenTelemetryLoggingExtensions.cs	100.00% <100.00%> (ø)
src/OpenTelemetry/Logs/OpenTelemetryLogger.cs	86.66% <0.00%> (-4.45%)	⬇️
...Telemetry/Internal/SelfDiagnosticsEventListener.cs	96.87% <0.00%> (-0.79%)	⬇️
...tation/OpenTelemetryProtocolExporterEventSource.cs	85.00% <0.00%> (+10.00%)	⬆️

[alanwest]

🥳 🎉

[alanwest]

LGTM