[Feature]: add nesting option to Map/Parallel

[yaythomas]

What would you like?

A way to config Ma/Parallel to create nesting for each iteration/branch or keep it flat and lower the cost and increase max iterations possible

Similar to

• feat(sdk): add nesting option to Map/Parallel aws-durable-execution-sdk-js#456
• [feat]: support FLAT nesting type for map/parallel aws-durable-execution-sdk-java#335

Possible Implementation

No response

Is this a breaking change?

No

Does this require an RFC?

No

Additional Context

No response