Add DRBG test components

[ronald-cron-arm]

• Add PSA_CRYPTO_ENTROPY_FORCE_SHA256 config option and its documentation in the section "PSA cryptography core configuration options" of crypto_config.h. Similar to MBEDTLS_ENTROPY_FORCE_SHA256 in mbedtls. Disabled by default.
• Add PSA_CRYPTO_CTR_DRBG_USE_128_BIT_KEY config option and its documentation in the section "PSA cryptography core configuration options" of crypto_config.h. Similar to MBEDTLS_CTR_DRBG_USE_128_BIT_KEY in mbedtls. Disabled by default.
• Take into account PSA_CRYPTO_ENTROPY_FORCE_SHA256 and PSA_CRYPTO_CTR_DRBG_USE_128_BIT_KEY in RNG/DRBG pre-processor logic (see #if defined(PSA_CRYPTO_EXTERNAL_RNG) in config_adjust_mbedtls_from_psa_crypto.h.
• Add test_hmac_drbg test component similar to test_no_ctr_drbg_use_psa in mbedtls.
• Add test_hmac_drbg_aes_only_128_bit_keys test component similar to test_no_ctr_drbg_aes_only_128_bit_keys in mbedtls.
• Add test_ctr_drbg_aes_256_sha_256, test_ctr_drbg_aes_128_sha_512 and test_ctr_drbg_aes_128_sha_256 similar to the mbedtls ones
• Add test_psa_external_rng test component equivalent to test_rng_no_drbg_use_psa and test_psa_external_rng_use_psa_crypt
• Check that the test components do what they intend to do and give evidence of this in this issue or the associated PR for the benefit of reviewers

Notes:

• In psa-crypto the selection between CTR_DRBG and HMAC_DRBG is done through PSA_CRYPTO_HMAC_DRBG_HASH (see crypto_config.h)
• No need for test_no_ctr_drbg_use_psa and test_no_hmac_drbg_use_psa equivalents as in psa-crypto there is no configuration option to enable or disable the CTR_DRBG and HMAC_DRBG modules.

Depends on:

• Add support for psa-crypto in config.py #58 to set up the full config
• Add AES related test components #65 for PSA_CRYPTO_AES_ONLY_128_BIT_KEY_LENGTH