Update and Refactor find_MAP and fit_laplace (#531)

* Move laplace and find_map to submodule

* Split idata utilities into `idata.py`

* Refactor find_MAP

* Refactor fit_laplace

* Update better-optimize version pin

* Handle labeling of non-scalar RVs without dims

* Add unconstrained posterior draws/points to unconstrained_posterior

Author: jessegrabowski

pymc_extras/inference/__init__.py

@@ -12,9 +12,9 @@
 #   See the License for the specific language governing permissions and
 #   limitations under the License.
 
-from pymc_extras.inference.find_map import find_MAP
 from pymc_extras.inference.fit import fit
-from pymc_extras.inference.laplace import fit_laplace
+from pymc_extras.inference.laplace_approx.find_map import find_MAP
+from pymc_extras.inference.laplace_approx.laplace import fit_laplace
 from pymc_extras.inference.pathfinder.pathfinder import fit_pathfinder
 
 __all__ = ["fit", "fit_pathfinder", "fit_laplace", "find_MAP"]