pk: implement non-PSA mbedtls_pk_sign_ext()

This makes the function always available with its
its implementation depending on MBEDTLS_USE_PSA_CRYPTO.

Related dependencies and tests are updated as well.

Fixes #7583.

Signed-off-by: Tomi Fontanilles <129057597+tomi-font@users.noreply.github.com>
diff --git a/include/mbedtls/pk.h b/include/mbedtls/pk.h
index 24b1188..355bf10 100644
--- a/include/mbedtls/pk.h
+++ b/include/mbedtls/pk.h
@@ -28,7 +28,7 @@
 #include "mbedtls/ecdsa.h"
 #endif
 
-#if defined(MBEDTLS_USE_PSA_CRYPTO) || defined(MBEDTLS_PSA_CRYPTO_C)
+#if defined(MBEDTLS_PSA_CRYPTO_C)
 #include "psa/crypto.h"
 #endif
 
@@ -615,7 +615,6 @@
                     unsigned char *sig, size_t sig_size, size_t *sig_len,
                     int (*f_rng)(void *, unsigned char *, size_t), void *p_rng);
 
-#if defined(MBEDTLS_PSA_CRYPTO_C)
 /**
  * \brief           Make signature given a signature type.
  *
@@ -652,7 +651,6 @@
                         unsigned char *sig, size_t sig_size, size_t *sig_len,
                         int (*f_rng)(void *, unsigned char *, size_t),
                         void *p_rng);
-#endif /* MBEDTLS_PSA_CRYPTO_C */
 
 /**
  * \brief           Restartable version of \c mbedtls_pk_sign()