[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/strings.xml

@@ -475,8 +475,6 @@
     <string name="use_custom_rtc">Custom RTC</string>
     <string name="use_custom_rtc_description">Allows you to set a custom real-time clock separate from your current system time.</string>
     <string name="set_custom_rtc">Set custom RTC</string>
-    <string name="disable_nca_verification">Disable NCA Verification</string>
-    <string name="disable_nca_verification_description">Disables integrity verification of NCA content archives. This may improve loading speed but risks data corruption or invalid files going undetected. Some games that require firmware versions 20+ may need this as well.</string>
 
     <string name="generate">Generate</string>
 
@@ -785,9 +783,6 @@
     <string name="loader_requires_firmware">Game Requires Firmware</string>
     <string name="loader_requires_firmware_description"><![CDATA[The game you are trying to launch requires firmware to boot or to get past the opening menu. Please <a href="https://yuzu-mirror.github.io/help/quickstart"> dump and install firmware</a>, or press "OK" to launch anyways.]]></string>
 
-    <string name="nca_verification_disabled">NCA Verification Disabled</string>
-    <string name="nca_verification_disabled_description">This is required to run new games and updates, but may cause instability or crashes if NCA files are corrupt, modified, or tampered with. If unsure, re-enable verification in Advanced Settings -> System, and use firmware versions of 19.0.1 or below.</string>
-
     <!-- Intent Launch strings -->
     <string name="searching_for_game">Searching for game...</string>
     <string name="game_not_found_for_title_id">Game not found for Title ID: %1$s</string>