Delete some sample programs

[davidhorstmann-arm]

Part of implementing #9904

Delete the following programs from the programs/ directory:

• pkey/rsa_genkey.c
• pkey/pk_decrypt.c
• pkey/dh_genprime.c
• pkey/rsa_verify.c
• pkey/mpi_demo.c
• pkey/rsa_decrypt.c
• pkey/key_app.c
• pkey/dh_server.c
• pkey/ecdh_curve25519.c
• pkey/pk_encrypt.c
• pkey/rsa_sign.c
• pkey/key_app_writer.c
• pkey/dh_client.c
• pkey/ecdsa.c
• pkey/rsa_encrypt.c
• test/selftest.c
• wince_main.c
• aes/crypt_and_hash.c
• random/gen_random_ctr_drbg.c
• random/gen_entropy.c
• hash/md_hmac_demo.c
• hash/hello.c
• hash/generic_sum.c
• cipher/cipher_aead_demo.c

This task is done when the programs listed are removed and there is no mention of them in the build system / documentation / elsewhere (except the changelog).

Estimate: 2 Ideal Engineering Hours

[gilles-peskine-arm]

We should also update the relevant knowledge base entries. This may be another task though, we might even decide not to care at this time and then do a pass by document rather than by issue near the time of the release.

For this issue, I see dh_genprime mentioned in https://github.com/Mbed-TLS/mbedtls-docs/blob/main/kb/cryptography/providing-diffie-hellman-or-dhm-parameters.md which is fully obsolete in 1.0/4.0 (but should not be deleted as long as 3.6 is around), and selftest mentioned in a couple of documents. That's just from grepping programs/, I haven't tried grepping individual program names.

[davidhorstmann-arm]

I will add a separate task so that we can prioritize it separately.