video_core: Remove usages of System::GetInstance() within the engines

* Fixes Unicode Key File Directories

Adds code so that when loading a file it converts to UTF16 first, to
ensure the files can be opened. Code borrowed from FileUtil::Exists.

* Update src/core/crypto/key_manager.cpp

Co-Authored-By: Jungorend <Jungorend@users.noreply.github.com>

* Update src/core/crypto/key_manager.cpp

Co-Authored-By: Jungorend <Jungorend@users.noreply.github.com>

* Using FileUtil instead to be cleaner.

* Update src/core/crypto/key_manager.cpp

Co-Authored-By: Jungorend <Jungorend@users.noreply.github.com>

service/nvflinger: Relocate definitions of Layer and Display to the vi service

These are more closely related to the vi service as opposed to the
intermediary nvflinger.

This also places them in their relevant subfolder, as future changes to
these will likely result in subclassing to represent various displays
and services, as they're done within the service itself on hardware.

The reasoning for prefixing the display and layer source files is to
avoid potential clashing if two files with the same name are compiled
(e.g. if 'display.cpp/.h' or 'layer.cpp/.h' is added to another service
at any point), which MSVC will actually warn against. This prevents that
case from occurring.

This also presently coverts the std::array introduced within
f45c25aa back to a std::vector to allow
the forward declaration of the Display type. Forward declaring a type
within a std::vector is allowed since the introduction of N4510
(http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4510.html) by
Zhihao Yuan.

vk_resource_manager: Implement fence and command buffer allocator

audio_core/buffer: Make const and non-const getter for samples consistent

address_arbiter: Use nested namespaces where applicable

renderer_opengl: respect the sRGB colorspace for the screenshot feature

Port citra-emu/citra#4197: "threadsafe_queue: Add PopWait and use it where possible "

This way proper const/non-const selection can occur.

A fairly trivial change. Other sections of the codebase use nested
namespaces instead of separate namespaces here. This one must have just
been overlooked.

Avoids the use of the global accessor in favor of explicitly making the
system a dependency within the interface.

core_timing: De-globalize core_timing facilities

Gets rid of the largest set of mutable global state within the core.
This also paves a way for eliminating usages of GetInstance() on the
System class as a follow-up.

Note that no behavioral changes have been made, and this simply extracts
the functionality into a class. This also has the benefit of making
dependencies on the core timing functionality explicit within the
relevant interfaces.

Previously, we were completely ignoring for screenshots whether the game uses RGB or sRGB.
This resulted in screenshot colors that looked off for some titles.

gl_rasterizer_cache: Get rid of variable shadowing

gl_shader_decompiler: Re-implement TLDS lod

Handles a pool of resources protected by fences. Manages resource
overflow allocating more resources.

This class is intended to be used through inheritance.

CommitFence iterates a pool of fences until one is found. If all fences
are being used at the same time, allocate more.

A fence watch is used to keep track of the usage of a fence and protect
a resource or set of resources without having to inherit from their
handlers.

Fences take ownership of objects, protecting them from GPU-side or
driver-side concurrent access. They must be commited from the resource
manager. Their usage flow is: commit the fence from the resource
manager, protect resources with it and use them, send the fence to an
execution queue and Wait for it if needed and then call Release. Used
resources will automatically be signaled when they are free to be
reused.

VKResource is an interface that gets signaled by a fence when it is free
to be reused.

vulkan: Add dependencies and device abstraction

core_timing: Make EmptyTimedCallback a local variable

 threadsafe_queue: Remove NeedSize template parameter

Makes it consistent with the regular standard containers in terms of
size representation. This also gets rid of dependence on our own
type aliases, removing the need for an include.

The necessity of this parameter is dubious at best, and in 2019 probably
offers completely negligible savings as opposed to just leaving this
enabled. This removes it and simplifies the overall interface.

Given this is only used in one place, it can be moved closest to its
usage site.

Implement BGRA8 framebuffer format

renderer_opengl: Remove reference to global system instance

VKDevice contains all the data required to manage and initialize a
physical device. Its intention is to be passed across Vulkan objects to
query device-specific data (for example the logical device and the
dispatch loader).

We already store a reference to the system instance that the renderer is
created with, so we don't need to refer to the system instance via
Core::System::GetInstance()

core_timing: Rename CoreTiming namespace to Core::Timing

kepler_compute: Fixup assert and rename the engine

Avoids shadowing the members of the struct itself, which results in a
-Wshadow warning.

This file is intended to be included instead of vulkan/vulkan.hpp. It
includes declarations of unique handlers using a dynamic dispatcher
instead of a static one (which would require linking to a Vulkan
library).