shader: remaining decode and emitter fixes

Decode and SPIR-V emitter corrections this title's shaders need: image and
memory operand handling, scalar ALU forms, and the IR plumbing that goes with
them.

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

@@ -45,6 +45,7 @@ constexpr OpcodeMap SOP1_OPCODE_LIST[] = {
     {0x10u, Opcode::S_BCNT1_I32_B64},
     {0x13u, Opcode::S_FF1_I32_B32},
     {0x14u, Opcode::S_FF1_I32_B64},
+    {0x15u, Opcode::S_FLBIT_I32_B32},
     {0x16u, Opcode::S_FLBIT_I32_B64},
     {0x1bu, Opcode::S_BITSET0_B32},
     {0x1du, Opcode::S_BITSET1_B32},