Support TraceSource to be initialized from the app.config file

[steveharter]

Fixes#23937 (original issue)
Fixes#72967 (API)

Much of the code was ported from .NET Framework and refactored to support the three new events to allow the config system to update TraceSource and friends from the config file(s). Original port per @ericstj in the first commit.

To enable this functionality, TraceConfiguration.Register() must be called. This is a new API that is not present in .NET Framework.

There is potentially more tests around error handling that could be added:

• Bad XML validation.
• Validation and happy path validation of the Attributes + GetSupportedAttributes() pattern in Switch, TraceSource and TraceListener.
• Invalid constructor arguments in XML passed via initializeData.

[ghost]

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Issue Details

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WIP

Author:	steveharter
Assignees:	steveharter
Labels:	area-System.Diagnostics
Milestone:	-

[ghost]

Note regarding the new-api-needs-documentation label:

This serves as a reminder for when your PR is modifying a ref *.cs file and adding/modifying public APIs, to please make sure the API implementation in the src *.cs file is documented with triple slash comments, so the PR reviewers can sign off that change.

[ericstj]

cc @RussKie@JeremyKuhne since you're involved from Winforms side. @noahfalk was also involved from diagnostics side.

[RussKie]

Thank you.
From the description is not obvious whether consumers will be required to change the code to get it to work, or it will work seamlessly as before.

[steveharter]

Thank you.
From the description is not obvious whether consumers will be required to change the code to get it to work, or it will work seamlessly as before.

Good point - I'll add that to the description.

Customers will be required to call TraceConfiguration.Register()

[noahfalk]

This LGTM. I think our WinForms users are really going to appreciate it!

[steveharter]

Note to reviewers: there was supposedly support for a filemappingsize config entry in the System.Diagnostics section that was read by performance counters. However, that code was not functional so it was removed as explained in the newly created issue #73706 and in this code

[steveharter]

CI is green with exception of runtime-staging.

[Tanya-Solyanik]

This call causes Winforms test to fail - dotnet/winforms#7578

[danmoseley]

Do we need to do anything to help folks that are trying to port discover how to make this work? Is it sufficient to hope they find the original issue and navigate here?

Should we put an example in the RC1 release post?

[RussKie]

I believe @KlausLoeffelmann was able to devise a fix, so I think we're good now.

[danmoseley]

@RussKie what I'm asking is how a customer porting to .NET Core whose code fails at runtime with something similar to

Unhandled Exception: System.Configuration.ConfigurationErrorsException: Configuration system failed to initialize ---> System.Configuration.ConfigurationErrorsException: Unrecognized configuration section system.diagnostics.

... will learn that they need to use .NET 7+ and add a call to TraceConfiguration.Register()..?

@KlausLoeffelmann is not a typical customer.

[steveharter]

Breaking change doc: dotnet/docs#32147

[RussKie]

@steveharter just to confirm - the fix is only in .NET 7 and it's not available in the earlier versions, right?