[Prometheus] Remove shared project and move the shared code under listener project

[Yun-Ting]

Related to:

#3430 (comment)
#3497 (comment)
#3430 (comment)

Changes

Trying out another project setup for prometheus.

Move the files that were previously in OpenTelemetry.Exporter.Prometheus.Shared to be under the OpenTelemetry.Exporter.Prometheus.HttpListener project.
And removed OpenTelemetry.Exporter.Prometheus.Shared project and its corresponding test project.

OpenTelemetry.Exporter.Prometheus.AspNetCore now reference the shared code from the listener project.

For significant contributions please make sure you have completed the following items:

• Appropriate CHANGELOG.md updated for non-trivial changes
• Design discussion issue #
• Changes in public API reviewed

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (main@f21afc8). Click here to learn what that means.
The diff coverage is 75.00%.

@@           Coverage Diff           @@
##             main    #3503   +/-   ##
=======================================
  Coverage        ?   86.71%           
=======================================
  Files           ?      275           
  Lines           ?     9970           
  Branches        ?        0           
=======================================
  Hits            ?     8645           
  Misses          ?     1325           
  Partials        ?        0           

Impacted Files	Coverage Δ
...rometheusExporterMeterProviderBuilderExtensions.cs	100.00% <ø> (ø)
...metheus.AspNetCore/PrometheusExporterMiddleware.cs	67.85% <ø> (ø)
...orterHttpListenerMeterProviderBuilderExtensions.cs	57.14% <ø> (ø)
....Prometheus.HttpListener/PrometheusHttpListener.cs	81.57% <ø> (ø)
...ometheus.HttpListener/Shared/PrometheusExporter.cs	100.00% <ø> (ø)
...tpListener/Shared/PrometheusExporterEventSource.cs	27.77% <ø> (ø)
...s.HttpListener/Shared/PrometheusExporterOptions.cs	57.14% <ø> (ø)
...etheus.HttpListener/Shared/PrometheusSerializer.cs	78.21% <ø> (ø)
...eus.HttpListener/Shared/PrometheusSerializerExt.cs	100.00% <ø> (ø)
...HttpListener/Shared/PrometheusCollectionManager.cs	80.48% <75.00%> (ø)

[reyang]

Maybe put these files under a folder named Shared or Internal?

[Yun-Ting]

I've moved the shared files between AspNetCore and the HttpListener projects that reside in the OpenTelemetry.Exporter.Prometheus.HttpListener project to a folder called Shared. And from the AspNetCore project, grouped the referenced shared files in the Include folder.

[reyang]

Are the shared code actually removed from OpenTelemetry.Exporter.Prometheus.Shared by this PR?

[reyang]

Approving given it is better than the current layout. I think the public class under shared folder is something that should be fixed in the next PR.

[Yun-Ting]

Are the shared code actually removed from OpenTelemetry.Exporter.Prometheus.Shared by this PR?

It is now :-)