cose-c should link publicly to openssl/mbedtls

[BrianSipos]

The link directives listed below are currently marked PRIVATE but this adds burden to users of COSE-C that they must manually add openssl/mbedtls libraries to their own link directives. If these were switched to PUBLIC then CMake would take care of the transitive linking automatically.

COSE-C/src/CMakeLists.txt

Line 67 in 97d1805

target_link_libraries(${PROJECT_NAME} PRIVATE mbedtls)

COSE-C/src/CMakeLists.txt

Line 70 in 97d1805

target_link_libraries(${PROJECT_NAME} PRIVATE ${OPENSSL_LIBRARIES})