core/loader: Remove dependencies on the global system instance

Now all that remains is:

18 instances in file_sys code
14 instances in GDB stub code (this can be tossed wholesale)
4 instances in HLE code
2 instances in settings code.

 nca_patch: Reduce stack usage size within SearchBucketEntry()

cheat_engine: Remove unnecessary system argument to CheatParser's Parse function

Previously this function was using ~16KB of stack (16528 bytes), which
was caused by the function arguments being taken by value rather than by
reference.

We can make this significantly lighter on the stack by taking them by
reference.

This is only used internally and doesn't depend on any class state, so
we can make it fully internal.

We don't need to create two separate instantiations of the same code, we
can simply make the character template argument a regular function
parameter.

This isn't used within the function at all in any implementations, so we
can remove it entirely.

patch_manager: Minor cleanup

We make it explicit that we're truncating arithmetic here to resolve
compiler warnings (even if the sizes weren't u32/u64 arithmetic
generally promotes to int :<)

We can use these to avoid typing the same type redundantly. This way, if
these ever change, only a single location needs to be modified.

These functions are only used within this translation unit, so we can
make them internally linked.

crypto/key_manager: Remove dependency on the global system accessor

We can supply the content provider as an argument instead of hardcoding
a global accessor in the implementation.

kernel: Remove all dependencies on the global system instance

With this, the kernel finally doesn't depend directly on the global
system instance anymore.

service: Remove two usages of the global system accessor

kernel/scheduler: Use std::mutex instead of spin lock

Remove bad and useless packages from LGTM build

cmake: Update to Qt 5.12.8

bsd: Resolve a few warnings

audio_core: Apollo Part 1, AudioRenderer refactor

It still fails due to CMake version being 3.13.4, but at
least we are not ones to blame now.

Project Mjölnir: Part 2 - Controller Applet

configure_input_player: Resolve sign conversion warnings in UpdateMappingWithDefaults()

video_core: Remove all Core::System references in renderer

gc_adapter: Make DeviceConnected() a const member function

Removes more instances of reliance on global state.

This doesn't modify instance state, so it can be made const.

Previously the address provided to SendToImpl would never be propagated
to SendTo(). This fixes that.

Same behavior, less typing.

We can simplify this a little by explicitly specifying the typename for
the lambda function.

game_list_p: Mark some constants as constexpr

Now that the GPU is initialized when video backends are initialized,
it's no longer needed to query components once the game is running: it
can be done when yuzu is booting.

This allows us to pass components between constructors and in the
process remove all Core::System references in the video backend.