Everywhere: Add sv suffix to strings relying on StringView(char const*)

Each of these strings would previously rely on StringView's char const*
constructor overload, which would call __builtin_strlen on the string.
Since we now have operator ""sv, we can replace these with much simpler
versions. This opens the door to being able to remove
StringView(char const*).

No functional changes.

Kernel/FileSystem/Plan9FileSystem.h

@@ -135,7 +135,7 @@ private:
     ProtocolVersion m_remote_protocol_version { ProtocolVersion::v9P2000 };
     size_t m_max_message_size { 4 * KiB };
 
-    Mutex m_send_lock { "Plan9FS send" };
+    Mutex m_send_lock { "Plan9FS send"sv };
     Plan9FSBlockerSet m_completion_blocker;
     HashMap<u16, NonnullRefPtr<ReceiveCompletion>> m_completions;