Add local path to `simoc_abm` in Development

[granawkins]

I'm realizing that now, when we make changes to simoc-abm, you can't preview them in the frontend locally.

1. When you run locally (is there an environment flag? where should we check?)
2. Check for a sibling-directory called simoc-abm (just like simoc-web)
3. If so, add it to the front of sys.path

This should cause the existing import statements (e.g. from simoc_abm.agent_model import AgentModel) to pull from the local instance instead of pip.

[granawkins]

From meeting discussion:

• Can do locally with pip -e flag (details to follow)
• Should update Github Actions to allow deploying specific branches of simoc-abm

[ezio-melotti]

See https://pip.pypa.io/en/stable/topics/local-project-installs/
If you use -e edits will be reflected in real-time without having to reinstall after each change.