test: adapt modules to the new test infrastructure

This not only provides a structural improvement but also
allows us to (1) specify individual tests to run and (2)
execute each of them concurrently.

src/modules/ellswift/tests_impl.h

@@ -7,6 +7,7 @@
 #define SECP256K1_MODULE_ELLSWIFT_TESTS_H
 
 #include "../../../include/secp256k1_ellswift.h"
+#include "../../unit_test.h"
 
 struct ellswift_xswiftec_inv_test {
     int enc_bitmap;
@@ -433,4 +434,10 @@ void run_ellswift_tests(void) {
     }
 }
 
+/* --- Test registry --- */
+/* TODO: subdivide test in cases */
+static const struct tf_test_entry tests_ellswift[] = {
+    CASE(ellswift_tests),
+};
+
 #endif