Update the migration script to work with new psql db

[john-dupuy]

Leaving as a draft until we figure out the indexes we need.

Some things I considered:

• Only migrating run, result, and artifact files from the most recent 3 months (determined by the newest record in the MongoDB)
  • This will keep our initial DB size small and also vastly reduce the time to run the migration script
  • If we were to migrate everything it would take ~20 hrs I believe
• Adding a upload_date field to the artifact model
• Only migrating artifacts, we don't have many/any recent reports, so I thought it best to just migrate artifacts
• Not migrating any imports

I got many of the column indexes, but there are still the JSON indexes to consider.

@rsnyman I'd figure I make this part of ibutsu-server so that we can use the models' from_dict method that we have defined in the db models.

The pre-commit update is because I hit PyCQA/pycodestyle#373

[john-dupuy]

The foreign key constraint is causing some problems with bad data in my local database, I don't think we'll hit the same issues on prod (especially if we're ignoring the old stuff) but I just pulled the latest DB dump to test out tomorrow.

[rsnyman]

I made a couple suggestions :-)

[john-dupuy]

OK @rsnyman I think this is finally in the "final" state. I applied a similar logic for the artifact files that is done for the results so that we can avoid any foreign key constraint errors (i.e. getting a list of migrated results and searching for artifacts within that result list).