Refactor and optimise D3D11 refcounting implementation

* In heavy D3D11 workloads the refcounting overhead especially during fast
  binding changes was significant. Refactoring the refcounting to work on a
  different model and deferring destruction of objects removes most of the
  overhead.

util/test/tests/D3D11/D3D11_Refcount_Check.py

@@ -0,0 +1,33 @@
+import struct
+import math
+import renderdoc as rd
+import rdtest
+
+
+class D3D11_Refcount_Check(rdtest.TestCase):
+    demos_test_name = 'D3D11_Refcount_Check'
+
+    def get_capture_options(self):
+        # Ensure we enable API validation since the test relies on being able to query it
+        ret = rd.CaptureOptions()
+
+        ret.apiValidation = True
+        ret.debugOutputMute = False
+
+        return ret
+
+
+    def check_capture(self):
+        draw = self.find_draw("Color Draw")
+
+        self.check(draw is not None)
+
+        draw = draw.next
+
+        self.controller.SetFrameEvent(draw.eventId, False)
+
+        pipe: rd.PipeState = self.controller.GetPipelineState()
+
+        self.check_pixel_value(pipe.GetOutputTargets()[0].resourceId, 0.5, 0.5, [0.0, 1.0, 0.0, 1.0])
+
+        rdtest.log.success("Captured loaded with color as expected")