TESTS: Add a simple test for MODESENSE6 that we can read it and we get at least 3 bydet of mode data (minimum size, header only)

test-tool/iscsi-test-cu.h

@@ -56,6 +56,8 @@ void test_iscsi_cmdsn_toolow(void);
 
 void test_mandatory_sbc(void);
 
+void test_modesense6_all_pages(void);
+
 void test_nomedia_sbc(void);
 
 void test_orwrite_simple(void);