feat: update modusDB interface to driver and db

[jairad26]

Description

This PR updates the nomenclature from db and namespace to engine and namespace to better represent common DB terminology

it also removes the notion of opertaion on both the entities, all mutations, queries, and drop datas are conducted on namespaces. the engine is responsibile for drop all & maintaining namespaces & state

Checklist

• Code compiles correctly and linting passes locally
• For all code changes, an entry added to the CHANGELOG.md file describing and linking to
  this PR
• Tests added for new functionality, or regression tests for bug fixes added as applicable
• For public APIs, new features, etc., PR on docs repo
  staged and linked here