For each declared key type, generate test cases for psa_import_key and
psa_generate_key when the corresponding type is not supported.
Some special cases:
* Public keys can never be generated.
* Omit key types that Mbed TLS does not support at all.
* ECC and FFDH, which depend on a curve/group, are not covered yet.
The generated test cases are written to
tests/suites/test_suite_psa_crypto_not_supported.generated.data .
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>