[FEATURE] Add an API route for GET /complaints

[DMalone87]

As a user of the API, I would like to be able to request a subset of the complaints that exist in the database. To accommodate this, we should add an API route that can handle this request. The API route should accept the following filters:

• Source UID
• Source Type
• Officers Involved
• Category
• Reason for Conflict
• Outcome of Conflict
• Date GTE
• Date LTE

Example:

curl --request GET \
     --url 'http://127.0.0.1:5001/api/v1/complaints?source_type=government' \
     --header 'accept: application/json'

Additional context
Incident Routes - This will need to be converted to complaints.py
Complaint Model
GET Complaints API Docs

The API docs can be used as a guide for the expected behavior of the API.