paw: spkg: Create seperate strlib directory

Signed-off-by: Chloe M. <chloe@mensia.org>

paw/spkg/lib/strlib/strlen.c

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: RtlStrLen() implementation
+ * Author:      Chloe M.
+ */
+
+#include <string.h>
+
+USIZE
+RtlStrLen(const CHAR *String)
+{
+    USIZE Length = 0;
+
+    if (String == NULL) {
+        return 0;
+    }
+
+    while (String[Length++] != '\0')
+        ;
+
+    return Length;
+}