Adding OPENSSL_secure_zalloc and BIO_s_secmem

[smittals2]

Description of changes:

Added BIO_s_secmem and OPENSSL_secure_zalloc. These functions are related to Secure Heaps which aren't supported in AWS-LC. Therefore, these functions use their normal alternatives (BIO_s_mem and OPENSSL_zalloc).

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 77.17%. Comparing base (c5d38a5) to head (69a0fbf).

Files	Patch %	Lines
crypto/bio/bio_mem.c	0.00%	2 Missing ⚠️
crypto/mem.c	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1476      +/-   ##
==========================================
- Coverage   77.18%   77.17%   -0.01%     
==========================================
  Files         426      426              
  Lines       71449    71452       +3     
==========================================
  Hits        55146    55146              
- Misses      16303    16306       +3     

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[samuel40791765]

Not trying to nitpick the wording here. But in the PR description and final commit message, could we replace "un-secure alternatives" with something else? It could make things seem scary and insecure, but in reality we're just pointing to the traditional alternatives.
It'd also help to clarify that these are "no-ops" in the PR title, since we aren't actually implementing secure heap versions of the functions.