Draft: Fix return types of some Surreal methods

[Wouterkoorn]

Change some return types from List[Dict, Any] to Unions[Dict[str, Any], List[Dict, Any]], or the Optional[...], variant of that.

What is the motivation?

Fix the currently incomplete/wrong return type annotations of some Surreal (WS/RPC client) methods.
Improving developer experience of users.

Type of Change

• 📚 Examples / docs / tutorials / dependencies update
• 🔧 Bug fix (non-breaking change which fixes an issue)
• 🥂 Improvement (non-breaking change which improves an existing feature)
• 🚀 New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to change)
• 🔐 Security fix

What does this change do?

Changes the return type of some methods from List[Dict[str, Any]] to

• Union[Dict[str, Any], List[Dict[str, Any]]] for create, update, and merge
• Optional[Union[Dict[str, Any], List[Dict[str, Any]]]] for select and delete

What is your testing strategy?

mypy returned OK
pre-commit returned OK
./scripts/run_tests.sh returned OK

Is this related to any issues?

Yes: #97
This PR is regarding the first "1." propose solution in the above referenced issue.

Have you read the Contributing Guidelines?

• I have read the Contributing Guidelines