calibre: Remove libraries during uninstallation

Test:
1. Install Calibre, add a few books and libraries
2. Uninstall, then install Calibre
3. The default Library is present and empty

Signed-off-by: nbenedek <contact@nbenedek.me>
Reviewed-by: Sunil Mohan Adapa <sunil@medhas.org>

plinth/modules/calibre/__init__.py

@@ -16,7 +16,7 @@ from plinth.modules.users.components import UsersAndGroups
 from plinth.package import Packages
 from plinth.utils import format_lazy
 
-from . import manifest
+from . import manifest, privileged
 
 _description = [
     format_lazy(
@@ -106,6 +106,11 @@ class CalibreApp(app_module.App):
         if not old_version:
             self.enable()
 
+    def uninstall(self):
+        """De-configure and uninstall the app."""
+        super().uninstall()
+        privileged.uninstall()
+
 
 def validate_library_name(library_name):
     """Raise exception if library name does not fit the accepted pattern."""

plinth/modules/calibre/privileged.py

@@ -45,3 +45,9 @@ def delete_library(name: str):
     library = LIBRARIES_PATH / name
     shutil.rmtree(library)
     action_utils.service_try_restart(calibre.CalibreApp.DAEMON)
+
+
+@privileged
+def uninstall():
+    """Remove all libraries during uninstall."""
+    shutil.rmtree(LIBRARIES_PATH)