Add FRED detection

[riptl]

FRED (Flexible Return and Event Delivery) is a technology enabling
faster syscall returns and interrupt handling

Although this is a kernel extension, I still think it's relevant for a Go userland.

FRED provides a measurable speedup for syscalls, so Go monitoring tooling could flag if a FRED-supporting CPU runs a kernel without fred=on boot parameter.

I'm doing work with handwritten kernels in KVM guests hosted by a Go hypervisor, so it's also useful for that niche use case.

Name: Intel(R) Core(TM) Ultra 7 355
Vendor String: GenuineIntel
Vendor ID: Intel
PhysicalCores: 8
Threads Per Core: 1
Logical Cores: 8
CPU Family 6 Model: 204 Stepping: 3
Features: ADX,AESNI,AVX,AVX2,AVXIFMA,AVXNECONVERT,AVXVNNI,AVXVNNIINT8,AVXVNNIINT16,BHI_CTRL,BMI1,BMI2,CETIBT,CETSS,CLMUL,CMOV,CMPCCXADD,CMPXCHG8,CX16,ERMS,F16C,FLUSH_L1D,FMA3,FRED,FSRM,FXSR,FXSROPT,GFNI,HRESET,HYBRID_CPU,IA32_ARCH_CAP,IA32_CORE_CAP,IBPB,IDPRED_CTRL,LAHF,LAM,LZCNT,MCDT_NO,MD_CLEAR,MMX,MOVBE,MOVDIR64B,MOVDIRI,NX,OSXSAVE,POPCNT,PSFD,RDRAND,RDSEED,RDTSCP,RRSBA_CTRL,SERIALIZE,SHA,SM3_X86,SM4_X86,SPEC_CTRL_SSBD,SSE,SSE2,SSE3,SSE4,SSE42,SSSE3,STIBP,STOSB_SHORT,SYSCALL,SYSEE,VAES,VMX,VPCLMULQDQ,WAITPKG,WBNOINVD,X87,XGETBV1,XSAVE,XSAVEC,XSAVEOPT,XSAVES,PMU_FIXEDCOUNTER_CYCLES,PMU_FIXEDCOUNTER_REFCYCLES,PMU_FIXEDCOUNTER_INSTRUCTIONS,PMU_FIXEDCOUNTER_TOPDOWN_SLOTS
Microarchitecture level: 3
Cacheline bytes: 64
L1 Instruction Cache: 65536 bytes
L1 Data Cache: 49152 bytes
L2 Cache: 3145728 bytes
L3 Cache: 12582912 bytes
Frequency: 3300000000 Hz
Boost Frequency: 4700000000 Hz
PMU version: 6 Fixed Counters: 3 General Purpose Counters: 8

Above is an Intel Panther Lake CPU with FRED support. It was quite hard to obtain due to Intel's incredibly low production volume. Happy to provide a CPUID dump if you want to add this to regression tests.