Support for SciPy sparse arrays

See also LiberTEM/LiberTEM#1684

Probably one will have to do a two-step rollout, first making the constants
available and then incluing them in BACKEND_ALL?

src/libertem_live/udf/monitor.py

@@ -19,7 +19,11 @@ def get_backends(self):
         ''
         return [
             backend for backend in self.BACKEND_ALL
-            if backend not in {self.BACKEND_CUPY_SCIPY_COO, self.BACKEND_SCIPY_COO}
+            if backend not in {
+                self.BACKEND_CUPY_SCIPY_COO,
+                self.BACKEND_SCIPY_COO,
+                self.BACKEND_SCIPY_COO_ARRAY
+            }
         ]
 
     # def get_preferred_input_dtype(self):
@@ -36,7 +40,7 @@ def process_tile(self, tile):
         ''
         # Assign the portion from the last frame within the tile
         # to the result buffer
-        self.results.intensity[:] = self.forbuf(tile[-1], self.results.intensity)
+        self.results.intensity[:] = self.forbuf(tile[[-1]], self.results.intensity)
 
     def merge(self, dest, src):
         ''