- Made LoadKernelSystemMode return a pair consisting of a system mode and a result code (Could use review).
- Deleted ErrorOpenGL error code in favor of just having ErrorVideoCore.
- Made dialog messages more clear.
- Compared archive ID in fs_user.cpp to ArchiveIdCode::NCCH as opposed to hex magic.
- Cleaned up some other stuff.

Corrects a few issues with regards to Doxygen documentation, for example:

- Incorrect parameter referencing.
- Missing @param tags.
- Typos in @param tags.

and a few minor other issues.

3dsx and elf files default to system mode 2 (96MB allocated to the application).

This allows Home Menu to boot without modifications.
Closes #1849

3dsx and elf files default to system mode 2 (96MB allocated to the application).

This allows Home Menu to boot without modifications.
Closes #1849

This makes clang-format useful on those.

Also add a bunch of forgotten transitive includes, which otherwise
prevented compilation.

Also rewrite Qt wrappers to use those.

This allows frontends to keep a single loader and use it multiple times
e.g. for code loading and SMDH parsing.

It is of very limited practical utility currently, and will soon be
impossible to support due to more accurate memory map emulation.

Loader: Keep a reference to the file and pass it to the correct AppLoader, instead of loading it multiple times.

- Useful for debugging homebrew

Qt: Updated GUI to support loading .bin files.

- Useful for debugging homebrew

Qt: Updated GUI to support loading .bin files.

- Required "file" handle to be made local and explicitly opened/closed as needed

NCCH: Removed extra qualification ‘Loader::AppLoader_NCCH::’.

NCCH: Updated LoadExec to use Memory::WriteBlock function to load binary code.

Loader: Added ErrorNotUsed ReturnStatus type to specify when something is not used.

- Various cleanups/refactorings to Loader, ELF, and NCCH modules.
- Added AppLoader interface to ELF and NCCH.
- Updated Qt/GLFW frontends to check AppLoader ResultStatus.

NCCH: Removed extra qualification typos.

Loader: Removed unnecessary #include's.

NCCH: Improved readability of memcmp statements.

NCCH: Added missing space.

Elf: Removed unnecessary usage of unique_ptr.

Loader: Removed unnecessary usage of unique_ptr.