Refactor tests to decouple from global Application state

Commented out `driver ??= Application.Driver` assignments in
`DriverAssert` to prevent automatic global driver assignment.
Removed `Application.ResetState(true)` calls and commented out
state validation assertions in `GlobalTestSetup` to reduce
dependency on global state.

Reintroduced `ApplicationForceDriverTests` and
`ApplicationModelFencingTests` to validate `ForceDriver` behavior
and ensure proper handling of legacy and modern Application
models. Skipped certain `ToAnsiTests` that rely on `Application`.

Removed direct `Application.Driver` assignments in
`ViewDrawingClippingTests` and `ViewDrawingFlowTests`.
Performed general cleanup of redundant code and unused imports
to simplify the codebase.

Tests/UnitTestsParallelizable/View/Draw/ViewDrawingFlowTests.cs

@@ -613,7 +613,6 @@ public class ViewDrawingFlowTests () : FakeDriverBase
         IDriver driver = CreateFakeDriver (80, 25);
         var initialClip = new Region (driver.Screen);
         driver.Clip = initialClip;
-        Application.Driver = driver;
 
         var view = new View
         {
@@ -636,8 +635,6 @@ public class ViewDrawingFlowTests () : FakeDriverBase
         // Points inside the view should be excluded
         // Note: This test depends on the DrawContext tracking, which may not exclude if nothing was actually drawn
         // We're verifying the mechanism exists, not that it necessarily excludes in this specific case
-
-        Application.ResetState (true);
     }
 
     #endregion