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.Shader/CodeGen/Msl/HelperFunctions/FindLSB.metal

@@ -1,5 +0,0 @@
-template<typename T>
-inline T findLSB(T x)
-{
-    return select(ctz(x), T(-1), x == T(0));
-}

src/Ryujinx.Graphics.Shader/CodeGen/Msl/HelperFunctions/FindMSBS32.metal

@@ -1,5 +0,0 @@
-template<typename T>
-inline T findMSBS32(T x)
-{
-    return select(clz(T(0)) - (clz(x) + T(1)), T(-1), x == T(0));
-}

src/Ryujinx.Graphics.Shader/CodeGen/Msl/HelperFunctions/FindMSBU32.metal

@@ -1,6 +0,0 @@
-template<typename T>
-inline T findMSBU32(T x)
-{
-    T v = select(x, T(-1) - x, x < T(0));
-    return select(clz(T(0)) - (clz(v) + T(1)), T(-1), v == T(0));
-}

src/Ryujinx.Graphics.Shader/CodeGen/Msl/HelperFunctions/HelperFunctionNames.cs

@@ -1,10 +0,0 @@
-namespace Ryujinx.Graphics.Shader.CodeGen.Msl
-{
-    static class HelperFunctionNames
-    {
-        public static string FindLSB = "findLSB";
-        public static string FindMSBS32 = "findMSBS32";
-        public static string FindMSBU32 = "findMSBU32";
-        public static string SwizzleAdd = "swizzleAdd";
-    }
-}

src/Ryujinx.Graphics.Shader/CodeGen/Msl/HelperFunctions/Precise.metal

@@ -1,14 +0,0 @@
-template<typename T>
-[[clang::optnone]] T PreciseFAdd(T l, T r) {
-    return fma(T(1), l, r);
-}
-
-template<typename T>
-[[clang::optnone]] T PreciseFSub(T l, T r) {
-    return fma(T(-1), r, l);
-}
-
-template<typename T>
-[[clang::optnone]] T PreciseFMul(T l, T r) {
-    return fma(l, r, T(0));
-}

src/Ryujinx.Graphics.Shader/CodeGen/Msl/HelperFunctions/SwizzleAdd.metal

@@ -1,7 +0,0 @@
-float swizzleAdd(float x, float y, int mask, uint thread_index_in_simdgroup)
-{
-    float4 xLut = float4(1.0, -1.0, 1.0, 0.0);
-    float4 yLut = float4(1.0, 1.0, -1.0, 1.0);
-    int lutIdx = (mask >> (int(thread_index_in_simdgroup & 3u) * 2)) & 3;
-    return x * xLut[lutIdx] + y * yLut[lutIdx];
-}