C interface for bytes functionality

[mellis13]

Description

In https://github.com/CrayLabs/SmartRedis/pull/521, functionality was added to operate on raw bytes in the C++ and Python clients. This ticket is for the addition of a similar C interface for these byte operations.

Justification

In an effort to provide a uniform experience across all clients, the C interface for byte operations should be implemented. Additionally, the C interface is a prerequisite for implementing the Fortran interface.

Implementation Strategy

The C++ interface for the bytes operations uses only void* pointers. As a result, minimal adaptation should be needed for the C.