amr to poly flatten examples generator

[cyrush]

gen_conduit_amr_flatten_examples.py

[cyrush]

@nselliott @agcapps

Following up on the amr example we discussed, the above python script is a work in progress to create the staged examples.

So far, we have:

• base amr mesh with a adjset and a nestset, as well as fields that help visualize these
• a split version of the amr mesh into smaller structured segments (but no extra metadata included)
  • to plumb this so it can be used with Noah's algorithm, we need to add the bespoke amr adjset window info
• a flattened fused polygonal mesh that includes an adjset and fields that help visualize the adjset

[cyrush]

I will create a branch for this, but need to think about where it belongs.