Refactor/Improve InvokeAsync to address potential disposing issues

[KlausLoeffelmann]

Addresses #12696, #12697
(Mentioning the latter just for same topic. I do not think, this is an issue really.)

Microsoft Reviewers: Open in CodeFlow

[Copilot]

Pull Request Overview

This PR refactors the InvokeAsync methods in Control_InvokeAsync.cs to address potential disposing issues and adds improved exception documentation.

• Added a null-check exception comment for the callback parameter.
• Inserted a handle creation check before invoking the asynchronous callback.
• Updated the cancellation token registration handling and its disposal pattern.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/System.Windows.Forms/System/Windows/Forms/Control_InvokeAsync.cs	Adds handle creation checks and adjusts cancellation token registration disposal in the async InvokeAsync implementations.
src/System.Windows.Forms/GlobalSuppressions.cs	Introduces new suppressions for CA2007 warnings on the InvokeAsync methods.

Comments suppressed due to low confidence (1)

src/System.Windows.Forms/System/Windows/Forms/Control_InvokeAsync.cs:186

• [nitpick] It may be beneficial to add a comment explaining that the cancellation token registration is disposed inside WrappedCallbackAsync to ensure proper unregistration and avoid potential disposal issues in asynchronous contexts.

using (registration)

[Copilot]

[nitpick] Consider whether to use ConfigureAwait(false) on the asynchronous lambda passed to BeginInvoke to avoid potentially capturing the synchronization context, unless this behavior is intentionally desired (noting that CA2007 warnings are suppressed).

Suggested change

	BeginInvoke(async () => await WrappedCallbackAsync());
	BeginInvoke(async () => await WrappedCallbackAsync().ConfigureAwait(false));

[KlausLoeffelmann]

We're already on the UI Thread, and the purpose is to marshal on the UI thread, so, FWIW ConfigureAwait(false) would not change anything.