searx: Completely uninstall app

* If only the SETTINGS_FILE gets removed, the setup
    process fails afterwards
* Don't remove the public access file since the setup process
    will remove it anyway

Test: Functional tests passed

Signed-off-by: nbenedek <contact@nbenedek.me>
[sunil: Update docstrings, make uninstall fail-safe]
Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: Sunil Mohan Adapa <sunil@medhas.org>

plinth/modules/searx/__init__.py

@@ -100,6 +100,11 @@ class SearxApp(app_module.App):
             self.enable()
             self.set_shortcut_login_required(True)
 
+    def uninstall(self):
+        """De-configure and uninstall the app."""
+        super().uninstall()
+        privileged.unininstall()
+
 
 class SearxWebserverAuth(Webserver):
     """Component to handle Searx authentication webserver configuration."""

plinth/modules/searx/privileged.py

@@ -153,3 +153,10 @@ def disable_public_access():
     """Disable public access to the SearX application."""
     if os.path.exists(PUBLIC_ACCESS_SETTING_FILE):
         os.remove(PUBLIC_ACCESS_SETTING_FILE)
+
+
+@privileged
+def unininstall():
+    """Remove configuration uWSGI file."""
+    shutil.rmtree('/etc/searx', ignore_errors=True)
+    pathlib.Path(UWSGI_FILE).unlink(missing_ok=True)