Add hook-info field-shape conformance handlers

[wangyb-A]

Summary

Adds 5 conformance handlers (handlers/plugin/plugin_{invocation_info,operation_info,attempt_info,operation_change,context_info}_shape.py) + template_plugin.yaml entries implementing plugin hook-info FIELD-SHAPE requirements 10-19..10-23 from aws/aws-durable-execution-conformance-tests#72 (land that PR first).

Each handler logs ONE single-line JSON record per hook event: a CANONICAL camelCase DUMP of that hook's own info parameter (None/unexposed fields OMITTED — a missing key fails its assertion). GA note: experimental payload fields (execution input/result, operation result) are still DUMPED when exposed but are not asserted by the requirements.

Live validation (us-west-2): 22/23 — ONE DELIBERATE FAILURE (SDK parity gap, tracked in #617)

• ❌ 10-19: Python's invocation infos expose no operations map and no externally-updated-operations collection (JS exposes both on every invocation hook). The dump omits those keys, failing the map-count assertions.
• ✅ 10-20..10-23 pass, plus the entire 10-1..10-18 regression.