Rework PSA curve to mbedlts group id conversion

Don't rely on the bit size encoded in the PSA curve identifier, in
preparation for removing that.

For some inputs, the error code on EC key creation changes from
PSA_ERROR_INVALID_ARGUMENT to PSA_ERROR_NOT_SUPPORTED or vice versa.
There will be further such changes in subsequent commits.
diff --git a/tests/suites/test_suite_psa_crypto.data b/tests/suites/test_suite_psa_crypto.data
index b70fc63..0205eea 100644
--- a/tests/suites/test_suite_psa_crypto.data
+++ b/tests/suites/test_suite_psa_crypto.data
@@ -304,11 +304,7 @@
 
 PSA import EC public key: key pair
 depends_on:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
-# For consistency with ECpub as ECpair, RSApub as RSApair and RSApair as RSApub,
-# one would expect the status to be PSA_ERROR_INVALID_ARGUMENT. But the
-# Mbed TLS pkparse module returns MBEDTLS_ERR_PK_INVALID_ALG, I think because
-# it's looking for an OID where there is no OID.
-import_with_data:"3078020101042100ab45435712649cb30bbddac49197eebf2740ffc7f874d9244c3460f54f322d3aa00a06082a8648ce3d030107a14403420004dea5e45d0ea37fc566232a508f4ad20ea13d47e4bf5fa4d54a57a0ba012042087097496efc583fed8b24a5b9be9a51de063f5a00a8b698a16fd7f29b5485f320":PSA_KEY_TYPE_ECC_PUBLIC_KEY(PSA_ECC_CURVE_SECP256R1):0:PSA_ERROR_NOT_SUPPORTED
+import_with_data:"3078020101042100ab45435712649cb30bbddac49197eebf2740ffc7f874d9244c3460f54f322d3aa00a06082a8648ce3d030107a14403420004dea5e45d0ea37fc566232a508f4ad20ea13d47e4bf5fa4d54a57a0ba012042087097496efc583fed8b24a5b9be9a51de063f5a00a8b698a16fd7f29b5485f320":PSA_KEY_TYPE_ECC_PUBLIC_KEY(PSA_ECC_CURVE_SECP256R1):0:PSA_ERROR_INVALID_ARGUMENT
 
 PSA import EC keypair: valid key but RSA
 depends_on:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_C:MBEDTLS_ECP_DP_BP512R1_ENABLED:MBEDTLS_RSA_C