Kernel: Use operator ""sv in all class_name() implementations

Previously there was a mix of returning plain strings and returning
explicit string views using `operator ""sv`. This change switches them
all to standardized on `operator ""sv` as it avoids a call to strlen.

Kernel/Net/TCPSocket.h

@@ -166,7 +166,7 @@ protected:
 
 private:
     explicit TCPSocket(int protocol, NonnullOwnPtr<DoubleBuffer> receive_buffer, NonnullOwnPtr<KBuffer> scratch_buffer);
-    virtual StringView class_name() const override { return "TCPSocket"; }
+    virtual StringView class_name() const override { return "TCPSocket"sv; }
 
     virtual void shut_down_for_writing() override;