Conversion of the EC tests to use the framework.

Some refactoring done as well.

The prime_field_tests() function needs splitting and refactoring still.
Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NAndy Polyakov <appro@openssl.org>
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3340)

test/build.info

@@ -67,7 +67,7 @@ INCLUDE_MAIN___test_libtestutil_OLB = /INCLUDE=MAIN
 
   SOURCE[ectest]=ectest.c
   INCLUDE[ectest]=.. ../include
-  DEPEND[ectest]=../libcrypto
+  DEPEND[ectest]=../libcrypto libtestutil.a
 
   SOURCE[ecdsatest]=ecdsatest.c
   INCLUDE[ecdsatest]=../include