DolphinQt: Use custom style for `QGroupBox` only with Qt 6.6.0+.
Improve usage of std::move and const references parameters
This is a follow-up to 3e788399b6f608a270fe0 (#14153), where a custom style for `QGroupBox` widgets was introduced when the Fusion style is used. However, it was overlooked that the custom QSS does not get along well with Qt versions older than 6.6.0; on Windows, Qt 6.5.1 is used. | With Qt 6.5.3 | With Qt 6.11.0 | | ------------- | -------------- | | <img alt="Dolphin with Qt 6.5.3" title="Dolphin with Qt 6.5.3" src="https://github.com/user-attachments/assets/9d341eef-0438-44c0-b341-8d0a53d9eb09" /> | <img alt="Dolphin with Qt 6.11.0" title="Dolphin with Qt 6.11.0" src="https://github.com/user-attachments/assets/1bc793d2-c958-413b-b99c-51d064104a75" /> | Compile checks have been added now to only apply the custom style if Qt 6.6.0 (or newer) is used.
Accomplished using `run-clang-tidy` with `performance-move-const-arg,performance-unnecessary-value-param,modernize-pass-by-value`. Changed arguments to const references, removed them where inappropriate (e.g. sink parameters). Same with std::move. Manually reviewed each change to make sure that it makes sense, and do something more appropriate if possible.
Fusion is the fallback style that Qt provides in systems that do not offer a OS-specific style. Basically, anything that is not Windows, macOS, or KDE (NOTE: Since #13919, users on these systems can opt in to Fusion too). Its default style for `QGroupBox` is not very conventional, and has been customized to align with more popular designs. | Before | After | | --- | --- | |  |  |
The status bar shows the number of games in your collection. If any games are hidden by the platform, region, or search filters it will also show how many games are visible and how many are filtered. The visibility of the status bar can be toggled from the menu by selecting `View`->`Show Game Count`. Implements https://bugs.dolphin-emu.org/issues/9517.
Yellow squiggly lines begone! Done automatically on .cpp files through `run-clang-tidy`, with manual corrections to the mistakes. If an import is directly used, but is technically unnecessary since it's recursively imported by something else, it is *not* removed. The tool doesn't touch .h files, so I did some of them by hand while fixing errors due to old recursive imports. Not everything is removed, but the cleanup should be substantial enough. Because this done on Linux, code that isn't used on it is mostly untouched. (Hopefully no open PR is depending on these imports...)
Core: Let any thread call previously host-thread-only functions