Support for the DIGEST module data type callback

[KarthikSubbarao]

Modules can support the DEBUG command on Module data type objects by implementing a Module data type callback. valkey-bloom implements a DIGEST Module data type callback and during a DEBUG operation, we would want to create and return a DIGEST.

This issue will add DIGEST support to the ValkeyModule-rs SDK with which DIGEST support can be added to valkey-bloom
valkey-io/valkeymodule-rs#97

[nnmehta]

Will pick this up