Revert the Metal Experiment (#701)

Metal sounded like a good idea to get in the emulator but frankly I
underestimated just how experimental and not ready it was.
From my write up in the Discord:
```
As is, Metal supports only a few games.
The games it does support freeze on first use of not playing them via Vulkan, because shader translation is broken.
So you need to use a dirty hack to not delete all your shaders.
Not to mention it breaks many games via MoltenVK because of changes to the shared GPU code.

Merging Metal seemed like a great idea, because of the few games it does support.
But I don't think it's worth it. Many of the games it breaks via MoltenVK *don't work via Metal*. 
Which effectively makes current Ryubing worse for Mac users than Ryujinx 1.1.1403.

I think what I'm gonna do is revert Metal, and reopen it as a PR. That way, you can still take advantage of the Metal backend as is, but without making other games worse with no solution.
```

For what it's worth, the shader translation part could at least be
"fixed" by always applying a 30ms delay for shader translation to Metal.
That being said, that solution sucks ass.
The MoltenVK regressions are even worse.



I hope this is not a let down to the Mac users. I hope you realize I'm
reverting this because you're actively getting a worse experience with
it in the emulator.

src/Ryujinx.Graphics.Metal/TextureBuffer.cs

@@ -1,132 +0,0 @@
-using Ryujinx.Common.Memory;
-using Ryujinx.Graphics.GAL;
-using SharpMetal.Metal;
-using System;
-using System.Runtime.Versioning;
-
-namespace Ryujinx.Graphics.Metal
-{
-    [SupportedOSPlatform("macos")]
-    class TextureBuffer : TextureBase, ITexture
-    {
-        private MTLTextureDescriptor _descriptor;
-        private BufferHandle _bufferHandle;
-        private int _offset;
-        private int _size;
-
-        private int _bufferCount;
-        private Auto<DisposableBuffer> _buffer;
-
-        public TextureBuffer(MTLDevice device, MetalRenderer renderer, Pipeline pipeline, TextureCreateInfo info) : base(device, renderer, pipeline, info)
-        {
-            MTLPixelFormat pixelFormat = FormatTable.GetFormat(Info.Format);
-
-            _descriptor = new MTLTextureDescriptor
-            {
-                PixelFormat = pixelFormat,
-                Usage = MTLTextureUsage.Unknown,
-                TextureType = MTLTextureType.TextureBuffer,
-                Width = (ulong)Info.Width,
-                Height = (ulong)Info.Height,
-            };
-
-            MtlFormat = pixelFormat;
-        }
-
-        public void RebuildStorage(bool write)
-        {
-            if (MtlTexture != IntPtr.Zero)
-            {
-                MtlTexture.Dispose();
-            }
-
-            if (_buffer == null)
-            {
-                MtlTexture = default;
-            }
-            else
-            {
-                DisposableBuffer buffer = _buffer.Get(Pipeline.Cbs, _offset, _size, write);
-
-                _descriptor.Width = (uint)(_size / Info.BytesPerPixel);
-                MtlTexture = buffer.Value.NewTexture(_descriptor, (ulong)_offset, (ulong)_size);
-            }
-        }
-
-        public void CopyTo(ITexture destination, int firstLayer, int firstLevel)
-        {
-            throw new NotSupportedException();
-        }
-
-        public void CopyTo(ITexture destination, int srcLayer, int dstLayer, int srcLevel, int dstLevel)
-        {
-            throw new NotSupportedException();
-        }
-
-        public void CopyTo(ITexture destination, Extents2D srcRegion, Extents2D dstRegion, bool linearFilter)
-        {
-            throw new NotSupportedException();
-        }
-
-        public ITexture CreateView(TextureCreateInfo info, int firstLayer, int firstLevel)
-        {
-            throw new NotSupportedException();
-        }
-
-        public PinnedSpan<byte> GetData()
-        {
-            return Renderer.GetBufferData(_bufferHandle, _offset, _size);
-        }
-
-        public PinnedSpan<byte> GetData(int layer, int level)
-        {
-            return GetData();
-        }
-
-        public void CopyTo(BufferRange range, int layer, int level, int stride)
-        {
-            throw new NotImplementedException();
-        }
-
-        public void SetData(MemoryOwner<byte> data)
-        {
-            Renderer.SetBufferData(_bufferHandle, _offset, data.Memory.Span);
-            data.Dispose();
-        }
-
-        public void SetData(MemoryOwner<byte> data, int layer, int level)
-        {
-            throw new NotSupportedException();
-        }
-
-        public void SetData(MemoryOwner<byte> data, int layer, int level, Rectangle<int> region)
-        {
-            throw new NotSupportedException();
-        }
-
-        public void SetStorage(BufferRange buffer)
-        {
-            if (_bufferHandle == buffer.Handle &&
-                _offset == buffer.Offset &&
-                _size == buffer.Size &&
-                _bufferCount == Renderer.BufferManager.BufferCount)
-            {
-                return;
-            }
-
-            _bufferHandle = buffer.Handle;
-            _offset = buffer.Offset;
-            _size = buffer.Size;
-            _bufferCount = Renderer.BufferManager.BufferCount;
-
-            _buffer = Renderer.BufferManager.GetBuffer(_bufferHandle, false);
-        }
-
-        public override void Release()
-        {
-            _descriptor.Dispose();
-
-            base.Release();
-        }
-    }
-}