feat: Implement 16 ListView CRUD events

[csharpfritz]

Closes FritzAndFriends#356

Completes EventArgs property parity for ListView CRUD events to match the System.Web.UI.WebControls originals.

All 16 events already wired with [Parameter] EventCallback declarations and HandleCommand routing. This PR adds missing dictionary properties to EventArgs types.

Changes:

• ListViewInsertEventArgs: add Values (IOrderedDictionary)
• ListViewUpdateEventArgs: add Keys, OldValues, NewValues (IOrderedDictionary)
• ListViewDeleteEventArgs: add Keys, Values (IOrderedDictionary)
• ListViewPagePropertiesChangingEventArgs: add TotalRowCount

In general, to fix a "useless assignment to local variable" you either remove the unused variable (if its value is not needed) or start using it meaningfully. Here, the test LayoutCreated_FiresWhenItemsExist never uses cut, and only needs the side effect of rendering the ListView to trigger OnLayoutCreated. The simplest, behavior‑preserving change is to call Render(...) without assigning its result to cut.

Concretely, in src/BlazorWebFormsComponents.Test/ListView/ListViewCrudEventTests.razor, within the LayoutCreated_FiresWhenItemsExist method (around line 658), replace var cut = Render(@<ListView ... with a bare Render(@<ListView ... call. No additional methods, imports, or definitions are required.

General fix: when a local variable is assigned a value that is never read, either remove the variable (and just execute the expression for its side effects) or, if the value is actually needed, add the missing read/use. Here, the expression Render(@<ListView ...>) is required for its side effects (rendering the component and triggering events), but the returned cut is not used, so we should remove the variable and keep just the call.

Best fix in this file: in LayoutCreated_DoesNotFireWhenItemsEmpty, change the line var cut = Render(...); to just Render(...);. This keeps the render side effect, preserves test behavior, and removes the unused local variable. No additional imports, methods, or definitions are needed; it's a single-line change within src/BlazorWebFormsComponents.Test/ListView/ListViewCrudEventTests.razor.

Concretely:

• In LayoutCreated_DoesNotFireWhenItemsEmpty (around line 672), replace the declaration/assignment var cut = Render(@<ListView ... with a standalone call Render(@<ListView ....
• The rest of the method and file remain unchanged.

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In general, to fix a "useless assignment to local variable" you either (1) remove the variable and just evaluate the expression for its side effects, if you don't need the result, or (2) start using the variable meaningfully if the result is actually needed. Here, the Render(...) call is required for its side effects (rendering the ListView and triggering data-bound events), but the cut variable itself is never used in DataBound_FiresAfterAllItemsRendered.

The best minimal fix without changing existing functionality is to remove the var cut = part and simply call Render(...) as a standalone statement. This preserves the render and event wiring but eliminates the unused local variable. Concretely, in src/BlazorWebFormsComponents.Test/ListView/ListViewCrudEventTests.razor, in the DataBound_FiresAfterAllItemsRendered method (starting at line 727), replace the line var cut = Render(@<ListView ... with Render(@<ListView ... and keep the rest of the method unchanged. No new imports, methods, or definitions are needed.

To fix this type of issue, you remove the unnecessary local variable or actually use it meaningfully. Here, the Render(...) call is needed (to perform the render and trigger data bound events), but the cut variable itself is not, since it is never read. The most direct fix that preserves all behavior is to keep the Render(...) call but drop the var cut = part.

Concretely, in src/BlazorWebFormsComponents.Test/ListView/ListViewCrudEventTests.razor, inside the DataBound_ItemDataBound_FiresPerItem test method, replace the line starting with var cut = Render(@<ListView ... with a call to Render(@<ListView ... without assigning to any variable. The rest of the method, including the subsequent assertion on _itemDataBoundCount, remains unchanged. No new imports, methods, or definitions are needed.

To fix the problem, the field _eventOrder should be declared as readonly so that its variable reference cannot be reassigned after initialization, while still allowing modifications to the list contents. This aligns with CodeQL’s recommendation and guards against accidental reassignment in future changes.

Concretely, in src/BlazorWebFormsComponents.Test/ListView/ListViewCrudEventTests.razor, within the @code block, update the declaration on line 13 from List<string> _eventOrder = new(); to readonly List<string> _eventOrder = new();. No other fields are flagged, and no additional methods, imports, or definitions are required, because readonly is a standard C# modifier and collection mutation (e.g., _eventOrder.Add(...)) remains fully supported.