feat: add campaign application

[gparlakov]

• start with adding the required tables in the db model
• why separate object
  • the campaign application will contain sensitive and personal documents that should not be made public
  • the lifecycle of the CampaignApplication is dictated by a process of ensuring the potential campaign is transparent and legitimate

work on CampaignApplication

Motivation and context

• start with adding the required tables in the db model
• why separate object
  • the campaign application will contain sensitive and personal documents that should not be made public
  • the lifecycle of the CampaignApplication is dictated by a process of ensuring the potential campaign is transparent and legitimate

  • Testing

Steps to test

New endpoints

Environment

New environment variables:

• [ ] NEW_ENV_VAR: env var details

New or updated dependencies:

Dependency name	Previous version	Updated version	Details
dependency/name	v1.0.0	v2.0.0

[github-actions[bot]]

✅ Tests will run for this PR. Once they succeed it can be merged.