FEX: Moves HostFeatures querying to the frontend

This moves the CPU feature querying to the frontend. The primary purpose
here is for the wow64 frontend to not require linux-isms for querying
these features. This is required since non-Linux environments don't have
the "CPUID" feature for reading EL1 MSRs in EL0.

Wiring up the remaining wow64 registry querying is left for a future
exercise.

This also technically removes an xbyak requirement from FEXCore for when
building the x86 Test harness runner, but that doesn't really matter for
regular use cases.

Source/Windows/ARM64EC/Module.cpp

@@ -25,6 +25,7 @@ $end_info$
 #include <FEXCore/Utils/TypeDefines.h>
 
 #include "Common/Config.h"
+#include "Common/HostFeatures.h"
 #include "Common/InvalidationTracker.h"
 #include "Common/TSOHandlerConfig.h"
 #include "Common/CPUFeatures.h"
@@ -468,6 +469,11 @@ NTSTATUS ProcessInit() {
   Exception::HandlerConfig.emplace();
 
   CTX = FEXCore::Context::Context::CreateNewContext();
+  {
+    auto HostFeatures = FEX::FetchHostFeatures();
+    CTX->SetHostFeatures(HostFeatures);
+  }
+
   CTX->SetSignalDelegator(SignalDelegator.get());
   CTX->SetSyscallHandler(SyscallHandler.get());
   CTX->InitCore();