Approximate explicit-LOD texture gathers at mip zero

Credits:
YuhiAida (@YuhiAida):
https://github.com/KytyPS5/KytyPS5/pull/588
https://github.com/KytyPS5/KytyPS5/pull/589
https://github.com/KytyPS5/KytyPS5/pull/655
frans (@francoisatt):
https://github.com/KytyPS5/KytyPS5/pull/590
BlackCAT (@psnwd):
https://github.com/KytyPS5/KytyPS5/pull/613
shadowbeat070 (@shadowbeat070):
https://github.com/KytyPS5/KytyPS5/pull/654
Pouare514 (@Pouare514):
https://github.com/KytyPS5/KytyPS5/pull/29
https://github.com/KytyPS5/KytyPS5/pull/32

src/graphics/shader/recompiler/frontend/decode/ImageOps.cpp

@@ -175,6 +175,7 @@ constexpr MimgSampleInfo MIMG_SAMPLE_OPCODE_LIST[] = {
 };
 
 constexpr MimgGatherInfo MIMG_GATHER_OPCODE_LIST[] = {
+    {0x44u, Opcode::IMAGE_GATHER4_L, ImageSampleFlagLod},
     {0x47u, Opcode::IMAGE_GATHER4_LZ, ImageSampleFlagLevelZero},
     {0x48u, Opcode::IMAGE_GATHER4_C, ImageSampleFlagCompare},
     {0x4fu, Opcode::IMAGE_GATHER4_C_LZ,

src/graphics/shader/recompiler/frontend/decode/ShaderDecoder.cpp

@@ -144,6 +144,7 @@ std::string FormatMimg(const Instruction& inst) {
 	}
 	switch (inst.opcode) {
 		case Opcode::IMAGE_SAMPLE:
+		case Opcode::IMAGE_GATHER4_L:
 		case Opcode::IMAGE_GATHER4_LZ:
 		case Opcode::IMAGE_GATHER4_C:
 		case Opcode::IMAGE_GATHER4_C_LZ:
@@ -580,6 +581,7 @@ std::string InstructionToString(const Instruction& inst) {
 		case Opcode::IMAGE_LOAD_MIP:
 		case Opcode::IMAGE_GET_RESINFO:
 		case Opcode::IMAGE_GET_LOD:
+		case Opcode::IMAGE_GATHER4_L:
 		case Opcode::IMAGE_GATHER4_LZ:
 		case Opcode::IMAGE_GATHER4_C:
 		case Opcode::IMAGE_GATHER4_C_LZ:

src/graphics/shader/recompiler/frontend/decode/ShaderDecoder.h

@@ -559,6 +559,7 @@ enum class Opcode {
 	IMAGE_ATOMIC_OR,
 	IMAGE_ATOMIC_XOR,
 	IMAGE_SAMPLE,
+	IMAGE_GATHER4_L,
 	IMAGE_GATHER4_LZ,
 	IMAGE_GATHER4_C,
 	IMAGE_GATHER4_C_LZ,