Update checks and rm commands in hooks: valid plugins are importer and diagnostic (not postprocessor)

This is more consistent with the structure of pysteps which has
io/importers
postprocessing/diagnostics

Author: ladc

hooks/post_gen_project.py

@@ -16,7 +16,8 @@ def remove_file(filepath):
 
 plugin_type = "{{ cookiecutter.plugin_type }}".lower()
 
-if plugin_type == "postprocessor":
-    shutil.rmtree("{{ cookiecutter.project_slug }}/importer")
-else:
-    shutil.rmtree("{{ cookiecutter.project_slug }}/postprocessor")
+VALID_PLUGIN_TYPES = ["importer", "diagnostic", "ensemblestat"]
+# Remove the plugin type that was not selected
+for plugin in VALID_PLUGIN_TYPES:
+    if plugin != plugin_type:
+        shutil.rmtree(f"{{ cookiecutter.project_slug }}/{plugin}")

hooks/pre_gen_project.py

@@ -13,7 +13,9 @@
     # Exit to cancel project
     sys.exit(1)
 
+VALID_PLUGIN_TYPES = ["importer", "diagnostic", "ensemblestat"]
+
 plugin_type = "{{ cookiecutter.plugin_type}}"
-if plugin_type != "importer" and plugin_type != "postprocessor":
-    print('\nERROR: The plugin_type must be "importer" or "postprocessor"')
-    sys.exit(1)
+if plugin_type not in VALID_PLUGIN_TYPES:
+    print(f'\nERROR: The plugin_type must be one of {", ".join(VALID_PLUGIN_TYPES)}')
+    sys.exit(1)