code: Use std::span where appropriate (#6658)

* code: Use std::span when possible

* code: Prefix memcpy and memcmp with std::

src/core/hle/kernel/thread.h

@@ -5,6 +5,7 @@
 #pragma once
 
 #include <memory>
+#include <span>
 #include <string>
 #include <unordered_map>
 #include <vector>
@@ -113,7 +114,7 @@ public:
     /**
      * Get a const reference to the thread list for debug use
      */
-    const std::vector<std::shared_ptr<Thread>>& GetThreadList();
+    std::span<const std::shared_ptr<Thread>> GetThreadList();
 
     void SetCPU(ARM_Interface& cpu_) {
         cpu = &cpu_;