Check application configuration hash when requesting application configuration

[nshyrei]

This PR returns back functionality to check if the application configuration struct from CCM is indeed the one that we expect to see when starting a user application inside Salmiac. The verification process involves comparing the SHA256 hash value of the application configuration structure with the SHA256 hash value passed by the user through ENCLAVEOS_APPCONFIG_ID or APPCONFIG_ID env var when starting Salmiac itself.

This hash check prevents malicious application configurations from being used when running a user application. Failure to pass the hash check results in no user application being run and Salmiac exiting with error code -1