HDR: Fix WIDE gamut mode with direct P3-to-2020 colour matrix (#18682)

Replace the incorrect two-step conversion (709->2020 then 2020->P3)
in the WIDE gamut mode with a single direct kP3to2020 matrix that
correctly converts DCI-P3 colour primaries into Rec.2020.

Add the kP3to2020 colour rotation matrix to HLSL (hdr_sm5.hlsl.h),
GLSL (hdr_common.glsl), and the Vulkan fragment shader (hdr.frag).
Rebuild SPIR-V shader binaries.

Author: MajorPainTheCactus

gfx/drivers/d3d_shaders/hdr_sm5.hlsl.h

@@ -111,6 +111,13 @@ static const float3x3 k709to2020 =
    { 0.0163916f, 0.0880132f, 0.8955950f }
 };
 
+static const float3x3 kP3to2020 =
+{
+   { 0.753833f,  0.198597f,  0.047570f },
+   { 0.045744f,  0.941777f,  0.012479f },
+   {-0.001210f,  0.017602f,  0.983609f }
+};
+
 static const float3x3 k2020toP3 = 
 {
    { 1.343578f, -0.282180f, -0.061399f },
@@ -184,12 +191,11 @@ float3 To2020(const float3 sdr_linear)
    }
    else if(global.expand_gamut == 1)
    {
-      rec2020 = mul( kExpanded709to2020, sdr_linear);
+      rec2020 = mul(kExpanded709to2020, sdr_linear);
    }
    else if(global.expand_gamut == 2)
    {
-      rec2020 = mul(k709to2020, sdr_linear);
-      rec2020 = mul(k2020toP3, rec2020);
+      rec2020 = mul(kP3to2020, sdr_linear);
    }
    else
    {
@@ -211,12 +217,11 @@ float4 To2020(const float4 sdr_linear)
    }
    else if(global.expand_gamut == 1)
    {
-      rec2020 = mul( kExpanded709to2020, sdr_linear.rgb);
+      rec2020 = mul(kExpanded709to2020, sdr_linear.rgb);
    }
    else if(global.expand_gamut == 2)
    {
-      rec2020 = mul(k709to2020, sdr_linear.rgb);
-      rec2020 = mul(k2020toP3, rec2020);
+      rec2020 = mul(kP3to2020, sdr_linear.rgb);
    }
    else
    {

gfx/drivers/vulkan_shaders/hdr.frag

@@ -118,8 +118,7 @@ vec3 To2020(const vec3 sdr_linear)
    }
    else if(gamut == 2u)
    {
-      rec2020 = sdr_linear * k709to2020;
-      rec2020 = rec2020 * k2020toP3;
+      rec2020 = sdr_linear * kP3to2020;
    }
    else
    {
@@ -147,8 +146,7 @@ vec4 To2020(const vec4 sdr_linear)
    }
    else if(gamut == 2u)
    {
-      rec2020 = sdr_linear.rgb * k709to2020;
-      rec2020 = rec2020 * k2020toP3;
+      rec2020 = sdr_linear.rgb * kP3to2020;
    }
    else
    {