UN-2278 post campaign supplier

[Kariamos]

This pull request introduces a new API endpoint for creating campaign finance suppliers, along with its implementation, OpenAPI documentation, schema updates, and comprehensive tests. The main focus is to allow authorized users to add new suppliers to a campaign, ensuring name uniqueness and proper permissions.

Key changes:

1. New API Endpoint for Creating Campaign Finance Suppliers

• Added the /campaigns/{campaign}/finance/supplier POST endpoint to the OpenAPI spec, enabling creation of new suppliers for a campaign with validation for required fields and security responses.
• Implemented the endpoint logic in SupplierRoute, including permission checks, duplicate name prevention, and error handling.
• Integrated the new endpoint into the TypeScript schema definitions, ensuring type safety and OpenAPI alignment. [1] [2]

2. Testing

• Added a comprehensive test suite for the new endpoint, covering permission scenarios, successful creation, duplicate prevention, and input validation.

3. Schema Enhancements

• Updated related schema fields with default values and improved documentation for better clarity and consistency in the API spec. [1] [2] [3] [4] [5] [6] [7]

These changes collectively introduce a robust and well-documented way to manage campaign finance suppliers via the API.

[github-actions]

Tests difference:

New Tests

< Enough permissions - admin - Should add new finance supplier
< Enough permissions - admin - Should not add existing supplier
< Enough permissions - admin - Should not add supplier with empty name
< Enough permissions - admin - Should return 200 if logged in as admin
< Enough permissions - olp - Should add supplier 
< Enough permissions - olp - Should not add existing supplier
< Not enough permissions - Should return 403 if logged in as not admin user
< Not enough permissions - Should return 403 if logged out
< Not enough permissions - Should return 403 if no access to the campaign

[coveralls]

coverage: 79.513% (+0.02%) from 79.494%
when pulling 7e105f7 on UN-2278-post-campaign-supplier
into bc0de18 on develop.