Fixes #4176. Removes View.MouseClick (#4450)

* Initial plan

* Add comprehensive MouseClick removal analysis

Co-authored-by: tig <585482+tig@users.noreply.github.com>

* Fix code review feedback on analysis document

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* Add actual line numbers to analysis document

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* Final polish on analysis document - clarify TextView

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* Phase 3: Port 6 simple Views from MouseClick to Selecting/MouseBindings

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* Phase 2: Port 10 Scenarios from MouseClick to Selecting/remove

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* Update analysis document - Phases 2 & 3 complete

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* Fix failing tests - Button multi-button support and Label focus handling

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* Phase 4: Port ScrollBar from OnMouseClick to OnSelecting; remove analysis doc

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* Phase 5: Update/remove tests that explicitly test MouseClick API

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* Code cleanup

* Remove MouseClick event

Consolidated mouse event handling by removing the `MouseClick`
event and integrating its functionality into the `MouseEvent`
event. Simplified `MouseEventArgs` documentation and added
support for invoking commands bound to mouse events.

Reorganized code by removing `Mouse Pressed Events` and
`Mouse Click Events` regions, introducing a new `WhenGrabbed
Handlers` region. Updated tests to replace `MouseClick` with
`MouseEvent`, adjusted test logic, and improved variable
naming for clarity.

Removed redundant assertions and unused code related to
`MouseClick`. Improved event propagation logic to ensure
proper handling of unhandled events. Performed general code
cleanup to enhance readability and maintainability.

* Updated deep dives.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: tig <585482+tig@users.noreply.github.com>
Co-authored-by: Tig <tig@users.noreply.github.com>

Tests/UnitTests/Application/Mouse/ApplicationMouseTests.cs

@@ -119,7 +119,7 @@ public class ApplicationMouseTests
 
         var mouseEvent = new MouseEventArgs { ScreenPosition = new (clickX, clickY), Flags = MouseFlags.Button1Clicked };
 
-        view.MouseClick += (s, e) =>
+        view.MouseEvent += (s, e) =>
                            {
                                Assert.Equal (expectedX, e.Position.X);
                                Assert.Equal (expectedY, e.Position.Y);