Make GARE validation as simple as possible

[sirosen]

This changeset completely replaces #795. I'm closing that as I think this is many times superior.

---

Rather than trying to build a framework, this is the "no framework" solution, in which we define very concrete helpers for very concrete purposes, including a dedicated one for the "ConsentRequired" Literal.

All of the GARE classes now inherit from an internal helper class, Serializable, which defines from_dict, to_dict, and _supported_fields in a generic way. The last of these does use some signature inspection magic, but nothing too abstruse.

The basic transformation is to replace each combination of a class-level annotation + a SUPPORTED_FIELDS entry with relevant assignment in __init__.

Some tangentially related simplifications and minor improvements are included:

• extra_fields -> extra

• Removal of unnecessary str splitting (after object is initialized)

• isinstance checking can also handle deserialization of dicts

• checking for non-null values will not accept session_message-only GARE data -- at least one of the semantic fields is required by the rewritten check

• GlobusAuthRequirementsError does not inherit from GlobusError or Exception -- it is not clear that this inheritance is useful or instructive to any user, since it mixes Exception hierarchies with data-representing hierarchies

• replace direct ValueError usage with a custom ValidationError class -- this avoids any messy scenarios in which a ValueError is accidentally introduced and incorrectly caught (e.g. from a stdlib call)

There are also some more significant improvements included. Most notably:

• Annotations explicitly do not accept None unless it is a valid value (i.e. annotations align with validation requirements)

• to_dict can now look for a concrete type (Serializable) and therefore can automatically invoke to_dict down a tree of objects

Although brevity is a non-goal of this changeset -- more verbose but clearer would be acceptable -- the result is almost 200 LOC lighter in the src/ tree. The primary ways in which things became shorter appear to be:

• explicit version is often much shorter than the framework-ized version (e.g. LegacyConsentRequiredAPError), and even where the two are close, the explicit version is shorter

• to_dict and from_dict centralization

---

📚 Documentation preview 📚: https://globus-sdk-python--796.org.readthedocs.build/en/796/

[ada-globus]

Can we make sure this updates the docs to reflect changes to the interfaces? (e.g.,

globus-sdk-python/docs/experimental/auth_requirements_errors.rst

Line 65 in 1488776

``GlobusAuthenticationParameters`` classes in an ``extra_fields`` attribute.

)