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

* code: Use std::span when possible

* code: Prefix memcpy and memcmp with std::

src/core/hle/kernel/kernel.h

@@ -8,6 +8,7 @@
 #include <atomic>
 #include <functional>
 #include <memory>
+#include <span>
 #include <string>
 #include <unordered_map>
 #include <vector>
@@ -230,7 +231,7 @@ public:
     /// Retrieves a process from the current list of processes.
     std::shared_ptr<Process> GetProcessById(u32 process_id) const;
 
-    const std::vector<std::shared_ptr<Process>>& GetProcessList() const {
+    std::span<const std::shared_ptr<Process>> GetProcessList() const {
         return process_list;
     }