Add mark to define per-test feature requirements

[lidavidm]

Instead of requiring pytest_generate_tests it would be great if we could do something more generic, like

@pytest.mark.needs_features(lambda features: features.statement_execute_schema and features.get_objects)
def test_foo(driver, conn):
    ...

# alternatively
@pytest.mark.needs_features(["statement_execute_schema", "get_objects"])
def test_foo(driver, conn):
    ...

Then we could have a generic generate_tests to handle most of these.