Get prod alias from --state manifest file when provided

[sebaap]

Is your feature request related to a problem? Please describe.
We have an uncommon BigQuery setup where our prod environment consist of multiple GCP projects, but dev is a single project. In this setup the name of the underneath tables for each model is different between the two environments, so currently data-diff doesn't work for us because it tries to use the same model alias in both environments.

Describe the solution you'd like
When providing a prod manifest via the --state, take the alias for prod from the manifest instead of using the same one from the run_results file. This should be fairly easy to implement and would allow us to use data-diff :)

Describe alternatives you've considered
With my very limited familiarity with the code, I don't see any other alternative to be honest.
Migrating to a single project setup is not an option for us as it would require a huge effort.

Additional context
I'm happy to submit a PR if help is needed, as I have a working version of this already.

[dlawin]

I think this was overlooked, no reason not to use the prod alias when we have the manifest here

data-diff/data_diff/dbt.py

Line 171 in eb22d3e

prod_database, prod_schema = _get_prod_path_from_manifest(model, dbt_parser.prod_manifest_obj)

[dlawin]

I'm happy to submit a PR if help is needed, as I have a working version of this already.

Please do and don't worry about the tests if some break, happy to take it the last mile