Introduce lazy_tree (super dictionaries)

[braingram]

Description

This PR adds:

• lazy_tree option to AsdfConfig
• lazy_tree argument to asdf.open (defaults to AsdfConfig.lazy_tree)
• Converter.lazy attribute used to indicate if a converter supports "lazy" objects
• asdf.lazy_nodes "lazy" container classes for list, dict, ordered dict

By default the "lazy" option is False.

When lazy_tree is True and an ASDF file is opened the tagged nodes in the tree are not immediately converted to custom objects. Instead, the containers in the tree (dicts, lists, OrderedDicts) are replaced with AsdfNode subclasses that act like these containers and convert tagged values to custom objects when they are accessed (See #1705 for discussion of this feature). During conversion, if asdf encounters a Converter that either defines lazy=False or does not define lazy the remainder of the branch will be converted to non-"lazy" objects and passed to the Converter. If instead the Converter defines lazy=True the "lazy" object (ie a AsdfDictNode for a dict) will be passed to the Converter.

Checklist:

• pre-commit checks ran successfully
• tests ran successfully
• for a public change, a changelog entry was added
• for a public change, documentation was updated
• for any new features, unit tests were added

[braingram]

converted to draft until #1733 (comment) is addressed

[braingram]

The following branch of roman_datamodels adds lazy to the node converters (and makes some minor node changes to account for AsdfDictNode not passing isinstance(..., dict) etc) to allow lazy loading of roman trees:
https://github.com/spacetelescope/roman_datamodels/compare/main...braingram:roman_datamodels:lazy?expand=1