Add setting to allow inactive users to login

[gabrielfgularte]

Issue: #745

Proposed changes

Adds a new settings ALLOW_INACTIVE_USERS_LOGIN and then check this setting on the on_complete method before the utils.user_is_active check.

Types of changes

Please check the type of change your PR introduces:

• Release (new release request)
• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (PEP8, lint, formatting, renaming, etc)
• Refactoring (no functional changes, no api changes)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Build related changes (build process, tests runner, etc)
• Other (please describe):

Checklist

• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works

Other information