Improve dev setup

[lucca65]

Story

Me as a developer contributing to Cambiatus backend
Want to be able to seed the database more easily
To improve my experience during development

Use cases

Given a new dev with a new env
When developing a new feature
Then I only need to run a seed file to fill basic necessary data

Issue description

Today our seeds file is used to setup new envs so it is very small and this is intended. However its common to have to setup a community to work on features so having a file like dev-seeds.exs would be incredible to improve the setup and experience to public contributors.

This was a request / suggestion from @ryguigas0 after he finished his contribution on #189