Add thin wrapper around advi functionality (#1365)

* Add thin wrapper around advi functionality

* Update ValueError string

* Update test_wrong_fit_method error string

* Ammend sampling from mean_field_approx

* Update pymc_marketing/clv/models/basic.py

Co-authored-by: Will Dean <57733339+wd60622@users.noreply.github.com>

* Parse _fit and _sample kwargs

* Rename fit

* Add fullrank. Gist notebook comparison

* Improve advi fit

* Fix plot label

* Add pcnt realtive diff between param estimates

* Add fullrank_advi to the test string

* Increase tolerance advi fit

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Co-authored-by: Will Dean <57733339+wd60622@users.noreply.github.com>
Co-authored-by: Juan Orduz <juanitorduz@gmail.com>