Support async operations on the server

[daniel-thom]

We are experiencing timeouts on larger workflows with some torc CLI commands. For example, torc workflows reinitialize on a workflow with 300k jobs times out. The delay is likely expected because of the SQL queries that run on the backend.

We can solve this by adding support for async operations. Possible flow:

• torc client submits reinitialize
• torc server receives the command, creates an async record in the database, returns the async ID, and starts the operation.
• torc client polls the server for that async ID until it completes. Or the client subscribes for an SSE event stream.
• torc server deletes the async record when it completes.

There are likely several operations that will need to move to this async paradigm.