If Dolphin crashes, changes that have been made to settings are often
lost. This has been a minor annoyance for me when developing, but it has
become a much bigger issue recently due to the problem where Dolphin
freezes on shutdown for ROG Ally users.

Instead of saving the config when certain arbitrary settings are
changed, let's save the config when the user closes the settings window.

The logic in the code was deliberately avoiding index `2` (**Selected
Font**; the debug font) by using `std::min(index, 1)`. Presumably, the
reason was that there was no debugger in Qt version of Dolphin at the
time.

Test plan:

- Select a debug font via the **Options > Font...** action.
- Show the **Log** tab via the **View > Log** action.
- In the **Log** tab, choose the **Selected Font** item in the combobox.
- Restart Dolphin.

**Without** the patch, the **Monospaced Font** item is wrongly selected
in the combobox.

**With** the patch, the **Selected Font** item is now properly restored
from the saved settings, and the selected debug font is correctly used
in the log messages.

Core: Add SDL Hints settings

Signed-off-by: Andrew Strauss <astrauss11@gmail.com>

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...)

Fix various typos and spelling mistakes