Walk inheritance hierarchy before checking is_dataclass in type_engine

[rahul-theorem]

TL;DR

Swap steps 3 & 4 in type_engine.py to walk the inheritance hierarchy to check for a registered TypeTransformer before checking is_dataclass

Type

• Bug Fix
• Feature
• Plugin

Are all requirements met?

• Code completed
• Smoke tested
• Unit tests added
• Code documentation added
• Any pending items have an associated Issue

Complete description

We have internal tooling which generates dataclasses from OpenAPI specifications, which all include a Generated mixin and are guaranteed to have a to_dict/from_dict method. We'd like to register a singletype transformer for all classes which have the Generated mixin instead of taking an extra dependency on dataclass-json; however, this isn't possible with the present implementation since the type engine checks is_dataclass before walking the inheritance hierarchy to resolve the type transformer.

This PR swaps this behavior so we can successfully detect a type transformer for Generated rather than falling back to the default dataclass serialization.

See https://flyte-org.slack.com/archives/CREL4QVAQ/p1666049599823129 for more details/discussion

Tracking Issue

N/A

Follow-up issue

N/A

[codecov]

Codecov Report

Merging #1239 (c760b39) into master (ab9aa65) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1239   +/-   ##
=======================================
  Coverage   68.68%   68.68%           
=======================================
  Files         288      288           
  Lines       26323    26323           
  Branches     2939     2939           
=======================================
  Hits        18079    18079           
  Misses       7766     7766           
  Partials      478      478           

Impacted Files	Coverage Δ
flytekit/core/type_engine.py	59.38% <100.00%> (ø)

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