Use standard CMake options to specify C/C++ language standard, add BoringSSL to speed test

[andrewhop]

Issues:

Resolves CryptoAlg-2257 CryptoAlg-1208

Description of changes:

1. Instead of specifying the direct C/C++ flags for language standard use the CMAKE_C_STANDARD option
2. Default to the same c99/c++11 but let AWS-LC builders override it
3. Update tool's CMakeList to search for libdecript and link it to any benchmark if found (needed for AES XTS and BoringSSL)
4. Add BoringSSL to the speed sanity test
5. Update the speed sanity test to build with C11 and C++14 (needed for BoringSSL which uses C11 features in their header files)

Call-outs:

BoringSSL already migrated to using CMAKE_C_STANDARD which we initially skipped because they also bumped up to C11 while we want to maintain C99 support.

Testing:

Built locally. Looking at the build out I verified the default and optional override are being set as expected:

1. cmake -GNinja
2. build.ninja contains -std=gnu99 and -std=gnu++11

With optional override:

1. cmake -GNinja -DCMAKE_CXX_STANDARD=14 -DCMAKE_C_STANDARD=11
2. build.ninja contains -std=gnu11 and -std=gnu++14

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 ✅

Comparison is base (71d119b) 76.84% compared to head (d9e06da) 76.81%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1410      +/-   ##
==========================================
- Coverage   76.84%   76.81%   -0.04%     
==========================================
  Files         425      425              
  Lines       71502    71502              
==========================================
- Hits        54948    54926      -22     
- Misses      16554    16576      +22     

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