Fix UAF in Delete wrappers, harden KDF and LMS signing

[JeremiahM37]

Addresses F-2605, F-2606, F-2607, F-2608, F-2609, F-2611, F-2615, F-2616

• Save heap before calling *_Free in wc_AesDelete, wc_HashDelete, wc_MlKemKey_Delete — prevents UAF if future Free zeroes the struct.
• Add NULL validation to wc_HKDF_Extract_ex (out, inKey/inKeySz) and to all four SRTP/SRTCP KDF public APIs (idx when kdrIdx >= 0).
• ForceZero the signature buffer on write_private_key failure in wc_LmsKey_Sign (native and external hash-sigs wrapper) to prevent OTS key reuse after NV rollback; matches existing XMSS pattern.

Added a few unit tests

[github-actions]

MemBrowse Memory Report

No memory changes detected for:

• gcc-arm-cortex-m4- gcc-arm-cortex-m4-baremetal- gcc-arm-cortex-m4-min-ecc- gcc-arm-cortex-m4-tls12

[wolfSSL-Fenrir-bot]

Fenrir Automated Review — PR #10238

Scan targets checked: wolfcrypt-api_misuse, wolfcrypt-bugs, wolfcrypt-compliance, wolfcrypt-concurrency, wolfcrypt-consttime, wolfcrypt-defaults, wolfcrypt-mutation, wolfcrypt-portability, wolfcrypt-proptest, wolfcrypt-src, wolfcrypt-zeroize

No new issues found in the changed files. ✅