feat: add missing data plane passthroughs and integration tests

[Hweinstock]

Issue #, if available: N/A

Description of changes:

Problem

MemoryClient exposes a subset of bedrock-agentcore data plane APIs via its passthrough mechanism, but 7 memory-related APIs are missing:

• batch_create_memory_records
• batch_delete_memory_records
• batch_update_memory_records
• start_memory_extraction_job
• list_memory_extraction_jobs
• list_sessions
• list_actors

Additionally, there is list_memory_strategies in the passthrough list, but it doesn't exist on the underlying client. So if a client calls this, it will fail at runtime.

Testing

Add integration tests covering some of the methods, all would be redundant as they are simple passthroughs.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (main@cd2f2a0). Learn more about missing BASE report.

Additional details and impacted files

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  Coverage        ?   90.92%           
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  Files           ?       43           
  Lines           ?     4112           
  Branches        ?      634           
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  Hits            ?     3739           
  Misses          ?      204           
  Partials        ?      169           

Flag	Coverage Δ
unittests	90.92% <ø> (?)

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