Optimize vk map generation

[eigmax]

Once we update circuits, it takes days to generate vk map.

We can introduce a dynamic vk generation mechanism:

1. Generate a small set of vk map;
2. Generate shape that we don't have a corresponding vk when we run prove_with_context;
3. Store the shape-wise vk in a database.

[eigmax]

For our current sample guest programs, the cloclz height may be 0.