[chore] Add tests and database configurations

**configurations**
```
* pytest
* database
* File upload folder path
```

**Configurations in more details**
The pytest to access all test configurations including the test databases, To set the default database for the app and to provide the path to the folder to store all of the platform's uploads.

**Describe alternatives you've considered**
Adding other database engines besides the default database.

Review the open linked pull request #1 first, since work is already underway. Use issue #10 as the acceptance outline: pytest should access the test configurations, the app should have a default database, and an upload-folder path should be configurable.

Written by the indexing model from the issue text.