[frontend, android] Move update_checker to frontend_common and add Android support (#2687)

I still have to add a setting to disable the auto update checking on a later PR, firstly lets make sure i didn't accidentally break anything  with CMAKE. or QT.

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/2687
Reviewed-by: Lizzie <lizzie@eden-emu.dev>
Reviewed-by: crueter <crueter@eden-emu.dev>
Co-authored-by: Inix <Nixy01@proton.me>
Co-committed-by: Inix <Nixy01@proton.me>

src/frontend_common/update_checker.h

@@ -0,0 +1,16 @@
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+// Copyright Citra Emulator Project / Azahar Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <optional>
+#include <string>
+
+namespace UpdateChecker {
+std::optional<std::string> GetResponse(std::string url, std::string path);
+std::optional<std::string> GetLatestRelease(bool include_prereleases);
+} // namespace UpdateChecker