[qt] refactor: qt_common lib (#94)

This is part of a series of PRs made in preparation for the QML rewrite. this PR specifically moves a bunch of utility functions from main.cpp into qt_common, with the biggest benefit being that QML can reuse the exact same code through ctx passthrough.

Also, QtCommon::Frontend is an abstraction layer over several previously Widgets-specific stuff like QMessageBox that gets used everywhere. The idea is that once QML is implemented, these functions can have a Quick version implemented for systems that don't work well with Widgets (sun) or for those on Plasma 6+ (reduces memory usage w/o Widgets linkage) although Quick from C++ is actually anal, but whatever.

Other than that this should also just kinda reduce the size of main.cpp which is a 6000-line behemoth rn, and clangd straight up gives up with it for me (likely caused by the massive amount of headers, which this DOES reduce).

In the future, I probably want to create a common strings lookup table that both Qt and QML can reference--though I'm not sure how much linguist likes that--which should give us a way to keep language consistent (use frozen-map).

TODO: Docs for Qt stuff

Co-authored-by: MaranBr <maranbr@outlook.com>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/94
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: Shinmegumi <shinmegumi@eden-emu.dev>

src/android/app/src/main/res/values-vi/strings.xml

@@ -482,8 +482,6 @@
     <string name="use_custom_rtc">RTC tuỳ chỉnh</string>
     <string name="use_custom_rtc_description">Cho phép bạn thiết lập một đồng hồ thời gian thực tùy chỉnh riêng biệt so với thời gian hệ thống hiện tại.</string>
     <string name="set_custom_rtc">Thiết lập RTC tùy chỉnh</string>
-    <string name="disable_nca_verification">Tắt xác minh NCA</string>
-    <string name="disable_nca_verification_description">Tắt xác minh tính toàn vẹn của kho lưu trữ nội dung NCA. Có thể cải thiện tốc độ tải nhưng có nguy cơ hỏng dữ liệu hoặc các tệp không hợp lệ không bị phát hiện. Cần thiết để các trò chơi và bản cập nhật yêu cầu firmware 20+ hoạt động.</string>
 
     <!-- Network settings strings -->
     <string name="generate">Tạo</string>