feature: support for reflecting db contents into another db

[edmundnoble]

This lets us for example reflect all of the things we read from one PactDb (like chainweb's) into another (like a pure one) for later use (for example in a unit test).

Change-Id: I476b90b2074ad2b6cd4de0b376931108181e638d

PR checklist:

• Test coverage for the proposed changes
• PR description contains example output from repl interaction or a snippet from unit test output
• New builtins have a FV translation
• Documentation has been (manually) updated at https://docs.kadena.io/pact
• Any changes that could be relevant to users have been recorded in the changelog
• In case of changes to the Pact trace output (pact -t), make sure pact-lsp is in sync.

Additionally, please justify why you should or should not do the following:

• Confirm replay/back compat
• Benchmark regressions
• (For Kadena engineers) Run integration-tests against a Chainweb built with this version of Pact