Move script `extract_component.py` to Overlap

Move script `extract_component.py` from directory Trajectories to
directory Overlap. It does not deal with trajectories and it does not
need the input graph to be a graph a segments.

Trajectories/Tests/tests.json

@@ -148,7 +148,7 @@
     {
 	"command":
 	[
-	    "$src_dir/Trajectories/extract_component.py",
+	    "$src_dir/Overlap/extract_component.py",
 	    "$my_data_dir/Eurec4A/Graph_anti/segments_cost.gt",
 	    "1980897", "component_1980897.graphml"
 	]