SP int: fixes from AI review

Re-implemented wc_PKCS12_PBKDF() to not use MP. Added tests to
unit.test.

sp_int.c:
  Fixes to comments.
  Added more define build options documentation to top of file.
  Fixes for builds with WOLFSSL_SP_INT_NEGATIVE defined.
Fixes for when a->used is 0 and no underflow - not actually a problem
but cleaner code.
  sp_sub has different checks on a->used when values are only positive.
  sp_dic_2d  missing check for e less than zero.
sp_to_unsigned_bin_len_ct: remove redundant check of outSz. Change i
to int to handle a->used of 0 and make code tidier.

Configuration testing fixes.
Fix formatting in test.c.
Added 128-bit types word128 and sword128 for cleaner PKCS#12 code.

Author: SparkiDev

.wolfssl_known_macro_extras

@@ -644,6 +644,7 @@ WC_NO_RNG_SIMPLE
 WC_NO_STATIC_ASSERT
 WC_NO_VERBOSE_RNG
 WC_PKCS11_FIND_WITH_ID_ONLY
+WC_PKCS12_PBKDF_USING_MP_API
 WC_PROTECT_ENCRYPTED_MEM
 WC_RNG_BLOCKING
 WC_RSA_NONBLOCK

tests/api.c

@@ -23560,7 +23560,7 @@ static int test_wolfSSL_X509_print(void)
 {
     EXPECT_DECLS;
 #if defined(OPENSSL_EXTRA) && !defined(NO_FILESYSTEM) && \
-   !defined(NO_RSA) && defined(XSNPRINTF)
+   !defined(NO_RSA) && defined(XSNPRINTF) && !defined(WC_DISABLE_RADIX_ZERO_PAD)
     X509 *x509 = NULL;
     BIO *bio = NULL;
 #if defined(OPENSSL_ALL) && !defined(NO_WOLFSSL_DIR)