Implement search provider (#201)

* Begin work on search provider

* Initial search provider work, organize meson

* Initial work on icons

* Implement LaunchSearch

* Don't hold arbitrary reference to service

I don't know why Lollypop does this

* Send notification, pad images

* Update translations

* Fix init_search_term typing

cartridges/store/managers/async_manager.py

@@ -0,0 +1,62 @@
+# async_manager.py
+#
+# Copyright 2023 Geoffrey Coulaud
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+from typing import Any, Callable
+
+from gi.repository import Gio
+
+from cartridges.game import Game
+from cartridges.store.managers.manager import Manager
+
+
+class AsyncManager(Manager):
+    """Manager that can run asynchronously"""
+
+    blocking = False
+    cancellable: Gio.Cancellable = None
+
+    def __init__(self) -> None:
+        super().__init__()
+        self.cancellable = Gio.Cancellable()
+
+    def cancel_tasks(self):
+        """Cancel all tasks for this manager"""
+        self.cancellable.cancel()
+
+    def reset_cancellable(self):
+        """Reset the cancellable for this manager.
+        Already scheduled Tasks will no longer be cancellable."""
+        self.cancellable = Gio.Cancellable()
+
+    def process_game(
+        self, game: Game, additional_data: dict, callback: Callable[["Manager"], Any]
+    ) -> None:
+        """Create a task to process the game in a separate thread"""
+        task = Gio.Task.new(None, self.cancellable, self._task_callback, (callback,))
+        task.run_in_thread(lambda *_: self._task_thread_func((game, additional_data)))
+
+    def _task_thread_func(self, data):
+        """Task thread entry point"""
+        game, additional_data, *_rest = data
+        self.run(game, additional_data)
+
+    def _task_callback(self, _source_object, _result, data):
+        """Method run after the task is done"""
+        callback, *_rest = data
+        callback(self)