A number of settings in the `debugger` group were wrongly using a newly constructed `QSettings` object instead of the singleton object that `GetQSettings()` provides. This made the application create a spurious, extra configuration file in the user directory: ``` ~/.config/Dolphin Emulator/dolphin-emu.conf ``` Notice that, by default, the application configuration files are stored in `~/.config/dolphin-emu`; not in `~/.config/Dolphin Emulator`.
In NandPaths.cpp, the `std::initializer_list<char>` of illegal characters has been turned into a `char[]` (similar to the one in GameList.cpp). The reverse iteration in ResourcePack.cpp seemed to provide no benefits, and doing without it it seemed to have no ill effects.
`std::erase` is a replacement for the remove-erase idiom. Changes to `OpenModeToAndroid` inadvertently revealed that the prior implementation had UB (potentially deleting the end iterator). This is now fixed.
Dolphin already uses QStyleHints::colorScheme to detect dark mode, so this code is now redundant.
Also clean up signals a bit.
This lets us reduce the number of USE_RETRO_ACHIEVEMENTS ifdefs in the code base, reducing visual clutter. In particular, needing an ifdef for each call to IsHardcodeModeActive was annoying to me. This also reduces the risk that someone writes code that accidentally fails to compile with USE_RETRO_ACHIEVEMENTS disabled. We could cut down on ifdefs even further by making HardcodeWarningWidget always exist, but that would result in non-trivial code ending up in the binary even with USE_RETRO_ACHIEVEMENTS disabled, so I'm leaving it out of this PR. It's not a lot of code though, so I might end up revisiting it at some point.