Checksum validation of resource binary files

As an extra layer of verification for resource binary files, particularly for the OTA update use case, it's desired that there's a checksum computed and kept alongside the resource binary data.

During resource initialization, the core library should then also compute the same checksum based on the actual resource binary data, and compare it against the expected checksum. If they don't match, an error should be reported (using the approach decided in QTMCU-349).