Allow user to skip test database creation per connection

[Harry Moreno]

I would like to specify in settings.py DATABASES variable that some database connection should be skipped for test database creation.

something like

# settings.py
DATABASES = {
  'secondary': {
    'TEST':  {
      'CREATE': False
    }
  }
}

This is necessary because my project has multiple database connections, some using a Readonly user on the database. When the test management command runs it attempts to create a test database using readonly credentials and the entire test suite fails. A user should be able to specify if a test database should not be created on a database.