Add unit tests for automated QA checks

[RickWangPerth]

This Pull Request adds unit tests(test_management_commands_auto_qa_checks.py) for the automated QA checks management command (automated_qa_checks.py) in the observations application. The following tests have been added:

• Tests for flagging turtle nest encounters with specific site names ('training' and 'testing').
• Tests for flagging turtle nest encounters with uncertain species, nesting outcomes, and nest age.
• Tests for flagging encounters with specific species in specific areas.
• Tests for marking imported turtle nest encounters as curated and flagging encounters with unknown reporters.