Modify dlopen.c and tfpsacrypto_dlopen.c so that they use PSA API-only dynamic loading

[ariwo17]

Description

• Replace soon-deprecated mbedtls_md_list() in dlopen.c with psa_hash_compute()
• Add tfpsacrypto_dlopen.c as a PSA-only shared-library loading test
• Enable -fPIC for tf-psa-crypto builtins to support shared linking
• Confirm clean builds and successful dlopen() test execution.

PR checklist

Please remove the segment/s on either side of the | symbol as appropriate, and add any relevant link/s to the end of the line.
If the provided content is part of the present PR remove the # symbol.

• changelog not required because this change is only to test programs
• development PR not required because this PR is targeting "development" directly
• TF-PSA-Crypto PR provided Use PSA API for demo in dlopen.c #10153
• framework PR not required
• 3.6 PR not required because this only applies to Mbed TLS 4.0
• tests not required because this is itself a runtime test rather than an automated test suite.

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