Consistent naming standard for private static fields

[JamesNK]

dotnet/aspnetcore mixes _underscore and PascalCase for private static fields. We should pick one for consistency and enable a naming rule to enforce it.

Search results: https://github.com/search?q=repo%3Adotnet%2Faspnetcore%20%22private%20static%20readonly%22&type=code

Note: dotnet/runtime uses s_ prefix.

[mkArtakMSFT]

Potentially related then #50854.
Is there more work to be done here, @JamesNK ?

[ghost]

Thanks for contacting us.

We're moving this issue to the .NET 9 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[JamesNK]

Potentially related then #50854. Is there more work to be done here, @JamesNK ?

That PR doesn't have a rule for private static fields.