Add data designer to ecosystem page

Use cases, pain points, and background
Data designer is used to generate synthetic datasets; it's relationship to NeMo Gym should be clarified

Description:
We should add Data Designer to the NVIDIA ecosystem page

Design:
ecosystem.md

Out of scope:
What are some items that this issue could be mistaken to cover that this issue should explicitly NOT cover?

Acceptance Criteria:

Individual items that need to be finished in order for this issue to be considered completed

Squashed commit of the following:

Refactor session cleanup and update example rollouts

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