Add callable helper for slow data generation

Some tests may fail a HealthCheck due to slow data generation - namely
any tests that try to generate an entire AfidSet. This commit adds a
function to the helpers that disables this check.

afids_utils/tests/helpers.py

@@ -36,3 +36,10 @@ def inner(callable: _T, /) -> _T:
         )(callable)
 
     return inner
+
+
+def slow_generation(callable: _T, /) -> _T:
+    """Disable health check for slow data generation tests"""
+    return settings(
+        suppress_health_check=[HealthCheck.too_slow],
+    )(callable)