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/FileSystem.h

@@ -67,7 +67,7 @@ protected:
     void set_block_size(u64 size) { m_block_size = size; }
     void set_fragment_size(size_t size) { m_fragment_size = size; }
 
-    mutable Mutex m_lock { "FS" };
+    mutable Mutex m_lock { "FS"sv };
 
 private:
     FileSystemID m_fsid;