Add finite float conversion methods in DICOM value types and use them in pixel data object attribute retrieval

[Enet4]

Summary

• [core] Reorganize PrimitiveValue methods into separate modules, so that the primitive module file isn't huge
• [core] add PrimitiveValue methods for conversion to finite float: to_finite_float32, to_finite_float64, to_multi_finite_float32, to_multi_finite_float64.
• [core] Extend these finite float conversion methods to DicomValue and DataElement
• [object] Add to_finite_f32 and to_finite_f64 to DicomAttribute trait
• [pixeldata] Use finite float conversion methods in pixel data object attribute retrieval, which prevents bad values in key attributes in the LUT processing steps from poisoning the pixel data samples