Idar oss/build error memcpy

[idarb-oss]

Fixes #985

Changes

Add include statement of cstring to opentelemetry-cpp/api/include/opentelemetry/common/kv_properties.h which caused build error for missing memcpy in scope.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Idar (08f4e75, 2f62332)

[ThomsonTan]

@idarb-oss thanks for your contribution. Please fix the CLA issue and resolve the conflict in the CHANGELOG file.

[idarb-oss]

@ThomsonTan CLA issue fixed and merge conflict resolved

[codecov]

Codecov Report

Merging #987 (459fa97) into main (5de793d) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #987   +/-   ##
=======================================
  Coverage   95.41%   95.41%           
=======================================
  Files         161      161           
  Lines        6833     6833           
=======================================
  Hits         6519     6519           
  Misses        314      314           

Impacted Files	Coverage Δ
api/include/opentelemetry/common/kv_properties.h	98.89% <ø> (ø)