Improve BC42328 documentation with comprehensive explanation of relaxed delegate conversions

[Copilot]

The BC42328 Visual Basic compiler warning documentation was minimal and didn't help developers understand when and why this warning occurs. Users reported confusion about:

• What "relaxed conversion" means in the context of delegates
• Why some similar AddHandler/RemoveHandler statements trigger the warning while others don't
• Why AddressOf is described as having "no effect" when it's syntactically required
• How to properly address the warning

Changes Made

Enhanced the BC42328.md documentation with:

Comprehensive explanation: Added detailed description of Visual Basic's relaxed delegate conversion feature, explaining the four types of conversions (widening parameters/return types, omitting parameters, dropping return values).

Clear examples: Provided concrete code examples showing when BC42328 occurs versus when it doesn't:

' Event delegate expects (sender As Object, e As EventArgs)
Public Event SomeEvent As EventHandler

' Method with exact signature - no warning
Sub Handler1(sender As Object, e As EventArgs)
    ' Implementation
End Sub

' Method with omitted parameters - causes BC42328
Sub Handler2()
    ' Implementation  
End Sub

' Using AddHandler with exact match - no warning
AddHandler SomeEvent, AddressOf Handler1

' Using AddHandler with relaxed conversion - causes BC42328
AddHandler SomeEvent, AddressOf Handler2

Clarification of "no effect" message: Explained why the compiler says AddressOf "has no effect" (because it must create a wrapper delegate regardless) while still being syntactically required.

Multiple correction strategies: Provided four different approaches for addressing the warning:

1. Variable assignment method (preserves exact semantics)
2. Exact signature matching
3. Lambda expression alternative
4. Handles clause approach

Practical guidance: Added section on when the warning can safely be ignored for common scenarios.

Enhanced cross-references: Added links to related Visual Basic documentation including relaxed delegate conversion, AddHandler/RemoveHandler statements.

The enhanced documentation transforms a confusing, minimal error page into a comprehensive resource that helps Visual Basic developers understand and properly handle BC42328 warnings.

Fixes #10157.

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Internal previews

📄 File	🔗 Preview link
docs/visual-basic/misc/bc42328.md	The 'AddressOf' expression has no effect in this context because the method argument to 'AddressOf' requires a relaxed conversion to the delegate type of the event

[BillWagner]

This is ready for final review once suggestions are applied.