feat: expose tuple hash calculation method

Picodata supports cluster-wide SQL and needs some predictable
method to calculate tuple hashes for the bucket ids. Method
should be available for Lua, C and Rust users. It was decided
to expose a murmur3 hash calculation method of the key_def module.

NO_DOC=picodata internal patch
NO_CHANGELOG=picodata internal patch

fix: tuple hash calculation tests

Tuple hash calculation tests for the C API were incorrect. Thanks
to the full pipeline with DEBUG build we detected the problem and
fixed it.

NO_DOC=picodata internal patch
NO_CHANGELOG=picodata internal patch