CLN: Separate spec and bbox derivation

This further breaks down the object data provider into a more refined
API and into more maintainable and testable blocks. An added benefit is
more type sanity.

src/fmu/dataio/_utils.py

@@ -13,6 +13,7 @@
 from pathlib import Path
 from typing import Any, Final, Literal
 
+import numpy as np
 import pandas as pd
 import xtgeo
 import yaml
@@ -25,6 +26,10 @@
 logger: Final = null_logger(__name__)
 
 
+def npfloat_to_float(v: Any) -> Any:
+    return float(v) if isinstance(v, (np.float64, np.float32)) else v
+
+
 def detect_inside_rms() -> bool:
     """Detect if 'truly' inside RMS GUI, where predefined variable project exist.