Dp/jacobian batched vmap

[dpanici]

This works well, this is LMN18 equilibrium solve with 1.5 oversampled grid and maxiter=10 memory trace vs time on GPU, where we get 4x memory decrease with negligible runtime increase:

Currently uses netket package for its chunked_vmap function, we don't want this as a dependency though so will try to implement a lighter weight version ourselves.

TODO

• [ ] re-implement without relying on netket
• [ ] change chunk_size to a better default value (something like 100 would be fine, maybe can dynamically choose based off of size of dim_x)
• [ ] Add chunk_size argument to every Objective class
• [ ] Add "chunked" as a deriv_mode to Derivative (or, just as an argument to Derivative to be used when "batched" is used)
• [ ] add to singular integral calculation as well

Resolves #826