kernel/hle_ipc: Convert std::shared_ptr IPC header instances to std::optional

video_core/gpu_thread: Silence a -Wreorder warning

video_core/gpu: Make GPU's destructor virtual

maxwell_to_vk: Initial implementation

dma_pusher: Store command_list_header by copy

Instead of holding a reference that will get invalidated by
dma_pushbuffer.pop(), hold it as a copy. This doesn't have any
performance cost since CommandListHeader is 8 bytes long.

There's no real need to use a shared lifetime here, since we don't
actually expose them to anything else. This is also kind of an
unnecessary use of the heap given the objects themselves are so small;
small enough, in fact that changing over to optionals actually reduces
the overall size of the HLERequestContext struct (818 bytes to 808
bytes).

For whatever bizarre reason, Apple only made a few of std::optional's
member functions available on newer SDK versions. Given we can't even
run yuzu on macOS, and we keep the builder around to ensure that it
always at least compiles on macOS, we can bump this up a version.

kernel/shared_memory: Get rid of the use of global accessor functions within Create()

This makes the class much more flexible and doesn't make performing
copies with classes that contain a bitfield member a pain.

Given BitField instances are only intended to be used within unions, the
fact the full storage value would be copied isn't a big concern (only
sizeof(union_type) would be copied anyways).

While we're at it, provide defaulted move constructors for consistency.

This function didn't have a definition, so we can remove it to prevent
accidentally attempting to use it.

Moves the data members to satisfy the order they're declared as in the
constructor initializer list.

Silences a -Wreorder warning.

Because of the recent separation of GPU functionality into sync/async
variants, we need to mark the destructor virtual to provide proper
destruction behavior, given we use the base class within the System
class.

Prior to this, it was undefined behavior whether or not the destructor
in the derived classes would ever execute.

web_browser: Add shortcut to Enter key to exit applet

kernel/client_session, kernel/server_session: Make data members private

yuzu: add a hotkey to switch between undocked and docked mode

service/audio/audout_u: Only actually stop the audio stream in StopAudioOut if the stream is playing

Asynchronous GPU command processing

service/audio/audout_u: Only actually stop the audio stream in StopAudioOut if the stream is playing

The service itself only does further actions if the stream is playing.
If the stream is already stopped, then it just exits successfully.

 gl_rasterizer_cache: Move format conversion functions to their own file 

core/hle/ipc: Remove unnecessary includes

core: Remove the global telemetry accessor function

kernel/address_arbiter: Convert the address arbiter into a class

hle/service/audio/audout_u: Correct lack of return in failure case of AppendAudioOutBufferImpl()

yuzu/debugger/wait_tree: Remove use of global CurrentProcess accessor

Previously we were overwriting the error case with a success code
further down (which is definitely not what we should be doing here).

svc: Move memory range checking functions to the VMManager class