More options for DADVI

[jessegrabowski]

I was playing around with DADVI and wanted the full range of optimizer options available in find_MAP, so I added them. These include:

• compile_kwargs
• gradient_backend (for MIT-MOT scan graphs in JAX mode until we fix that)
• basinhopping
• Results are now returned with a posterior group like all other PyMC inference methods
• If include_transform = True, the unconstrained draws are returned in an unconstrained_posterior group
• The optimizer_results are returned as an idata group

I also added tests for DADVI, mostly copy/paste from the find_MAP tests.

The result is some amount of code duplication with find_MAP, but I think it's acceptable.

cc @martiningram

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[jessegrabowski]

@maresb looks like the BLAS installation is failing on the new windows machines, is that known to us?

[ricardoV94]

The CI failing is unrelated to this PR, so I think it's fine to go ahead and merge