[processing][grass] Fix v.vect.stats output type, add test

(cherry-picked from b10fa5e)

python/plugins/processing/algs/grass7/ext/v_vect_stats.py

@@ -36,4 +36,4 @@ def processOutputs(alg, parameters, context, feedback):
     fileName = alg.parameterAsOutputLayer(parameters, 'output', context)
     grassName = alg.exportedLayers['areas']
     dataType = 'auto'
-    alg.exportVectorLayer(grassName, fileName, dataType)
+    alg.exportVectorLayer(grassName, fileName, dataType=dataType)

python/plugins/processing/tests/testdata/expected/grass7/v_vect_stats.prj

@@ -0,0 +1 @@
+GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]]

python/plugins/processing/tests/testdata/grass7_algorithms_vector_tests.yaml

@@ -114,3 +114,28 @@ tests:
       output:
         name: expected/grass7/v_what_rast.shp
         type: vector
+
+  - algorithm: grass7:v.vect.stats
+    name: v.vect.stats
+    params:
+      GRASS_MIN_AREA_PARAMETER: 0.0001
+      GRASS_OUTPUT_TYPE_PARAMETER: 0
+      GRASS_SNAP_TOLERANCE_PARAMETER: -1.0
+      GRASS_VECTOR_DSCO: ''
+      GRASS_VECTOR_LCO: ''
+      areas:
+        name: custom/zonal_stats.shp
+        type: vector
+      count_column: count
+      method: 0
+      points:
+        name: custom/grass7/sample_points.shp
+        type: vector
+      points_column: val
+      stats_column: stat
+      type:
+      - 0
+    results:
+      output:
+        name: expected/grass7/v_vect_stats.shp
+        type: vector