tests: Better suite creation

While the previous method of in-lining a stack allocated array of
tests into the suite struct declaration was nice, we had to update
size manually.

This macro will allow us to just append new tests to the suite without
having to care for that.  It generates a uniquely named variable for
the test array, then uses that test array in the suite declaration.
Nice and easy.

test/test_vec.c

@@ -69,15 +69,9 @@ void vec_test_substr(void)
   TEST_PASSED();
 }
 
-const test_suite_t VEC_SUITE = {
-    .name = "Vector Tests",
-    .tests =
-        (test_fn[]){
-            MAKE_TEST_FN(vec_test_concat),
-            MAKE_TEST_FN(vec_test_substr),
-        },
-    .size = 2,
-};
+MAKE_TEST_SUITE(VEC_SUITE, "Vector Tests",
+
+                MAKE_TEST_FN(vec_test_concat), MAKE_TEST_FN(vec_test_substr), );
 
 /* Copyright (C) 2026 Aryadev Chavali