Kernel: Make various T::class_name() and similar return StringView

Instead of returning char const*, we can also give you a StringView.

Kernel/Net/E1000ENetworkAdapter.h

@@ -27,7 +27,7 @@ public:
 
     virtual ~E1000ENetworkAdapter() override;
 
-    virtual const char* purpose() const override { return class_name(); }
+    virtual StringView purpose() const override { return class_name(); }
 
 private:
     E1000ENetworkAdapter(PCI::Address, u8 irq);

Kernel/Net/E1000NetworkAdapter.h

@@ -29,7 +29,7 @@ public:
     virtual void send_raw(ReadonlyBytes) override;
     virtual bool link_up() override;
 
-    virtual const char* purpose() const override { return class_name(); }
+    virtual StringView purpose() const override { return class_name(); }
 
 protected:
     void setup_interrupts();

Kernel/Net/IPv4Socket.h

@@ -75,7 +75,7 @@ public:
 
 protected:
     IPv4Socket(int type, int protocol);
-    virtual const char* class_name() const override { return "IPv4Socket"; }
+    virtual StringView class_name() const override { return "IPv4Socket"; }
 
     PortAllocationResult allocate_local_port_if_needed();
 

Kernel/Net/LocalSocket.h

@@ -52,7 +52,7 @@ public:
 
 private:
     explicit LocalSocket(int type);
-    virtual const char* class_name() const override { return "LocalSocket"; }
+    virtual StringView class_name() const override { return "LocalSocket"; }
     virtual bool is_local() const override { return true; }
     bool has_attached_peer(const FileDescription&) const;
     DoubleBuffer* receive_buffer_for(FileDescription&);

Kernel/Net/NE2000NetworkAdapter.h

@@ -25,7 +25,7 @@ public:
     virtual void send_raw(ReadonlyBytes) override;
     virtual bool link_up() override { return m_link_up; }
 
-    virtual const char* purpose() const override { return class_name(); }
+    virtual StringView purpose() const override { return class_name(); }
 
 private:
     NE2000NetworkAdapter(PCI::Address, u8 irq);

Kernel/Net/RTL8139NetworkAdapter.h

@@ -27,7 +27,7 @@ public:
     virtual void send_raw(ReadonlyBytes) override;
     virtual bool link_up() override { return m_link_up; }
 
-    virtual const char* purpose() const override { return class_name(); }
+    virtual StringView purpose() const override { return class_name(); }
 
 private:
     RTL8139NetworkAdapter(PCI::Address, u8 irq);

Kernel/Net/RTL8168NetworkAdapter.h

@@ -27,7 +27,7 @@ public:
     virtual void send_raw(ReadonlyBytes) override;
     virtual bool link_up() override { return m_link_up; }
 
-    virtual const char* purpose() const override { return class_name(); }
+    virtual StringView purpose() const override { return class_name(); }
 
 private:
     // FIXME: should this be increased? (maximum allowed here is 1024) - memory usage vs packet loss chance tradeoff

Kernel/Net/Socket.h

@@ -124,7 +124,7 @@ protected:
     size_t backlog() const { return m_backlog; }
     void set_backlog(size_t backlog) { m_backlog = backlog; }
 
-    virtual const char* class_name() const override { return "Socket"; }
+    virtual StringView class_name() const override { return "Socket"; }
 
     virtual void shut_down_for_reading() { }
     virtual void shut_down_for_writing() { }

Kernel/Net/TCPSocket.h

@@ -164,7 +164,7 @@ protected:
 
 private:
     explicit TCPSocket(int protocol);
-    virtual const char* class_name() const override { return "TCPSocket"; }
+    virtual StringView class_name() const override { return "TCPSocket"; }
 
     static NetworkOrdered<u16> compute_tcp_checksum(const IPv4Address& source, const IPv4Address& destination, const TCPPacket&, u16 payload_size);
 

Kernel/Net/UDPSocket.h

@@ -21,7 +21,7 @@ public:
 
 private:
     explicit UDPSocket(int protocol);
-    virtual const char* class_name() const override { return "UDPSocket"; }
+    virtual StringView class_name() const override { return "UDPSocket"; }
     static Lockable<HashMap<u16, UDPSocket*>>& sockets_by_port();
 
     virtual KResultOr<size_t> protocol_receive(ReadonlyBytes raw_ipv4_packet, UserOrKernelBuffer& buffer, size_t buffer_size, int flags) override;