Tracker issue for object API ergonomics

[Enet4]

Laying out some ideas and issues to keep in mind in order to improve the overall experience with the dicom-object API.

• Upper-level from_*/write/save functions could be more intuitive.
  • For example, reading from a file expects the file to have a preamble, whereas reading from an arbitrary reader does not (use dicom-rs with wasm bindgen #39).
  • One possible idea is to provide an options builder API which would allow the user to specify certain expectations regarding how the object should be read or written.
  • Object reading ergonomics are already improved in [object] Add OpenFileOptions #199
• Value conversion from retrieved attributes
  • One should have an easy way to convert data in an object's DICOM attributes from a textual format to a binary format and vice versa. This is particularly important for the plans in Interpreting string-based values? #9, so that decoding is postponed to the moment where the attribute is needed.
  • Resolved with On-demand primitive value conversion and construction #56, Preserve string values on data set reading #65, and [core] Add PrimitiveValue::to_multi_{date,time,datetime} #66.
• DicomObject trait is not sufficiently powerful enough to be usable.
  • It's lacking some useful methods because some of them not generic enough for future implementations.
  • The ideal set of definitions in this trait require generic associated types (GATs).
  • See Revise DicomObject abstraction #524