ENV vars for OPENSSL_NO_ASM

[justsmth]

Issues:

• Provides workaround for #376 (or for other platforms where AWS-LC assembly fails to build)

Description of changes:

• AWS-LC contains optimized assembly language implementations for many primitive cryptographic operations. As a fall-back, these operations also have a C-implementation provided.
• For most platforms, CMake correctly detects whether/which assembly files should be built. However, CMake's detection is sometimes inadequate or the build environment lacks an assembler (such as NASM), and the OPENSSL_NO_ASM flag must be passed to avoid build failures.
• The OPENSSL_NO_ASM flag may also be useful for debugging failing cryptographic operations.

Call-outs:

• The C-implementations are significantly slower than their assembly-language counterparts.
• The OPENSSL_NO_ASM flag is only allowed for un-optimized/debug builds.

Testing:

• Updated CI.

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

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 95.82%. Comparing base (972db16) to head (2d7fdb0).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #377 +/- ## ======================================= Coverage 95.82% 95.82% ======================================= Files 60 60 Lines 7865 7865 ======================================= Hits 7537 7537 Misses 328 328 ```

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