Support metric and loss kwargs

Support passing of class definitions and kwargs in configurations.

Currently, we use a mapper argument to map strings to metrics and losses since most class instances cannot be passed to trials (non-picklable). This will be replaced with passing class definitions or callables with kwargs.

For metrics - a list of dicts as below (metrics do not contain hyperparameters and can be stored in a list)

[{“name”: str, “metric”: class/callable, “kwargs”: dict}]

For losses - a single dict (multiple losses not supported):

{“name”: str, “loss”: class/callable, “kwargs”: dict}

Branch issue-30-Support_metric_and_loss_kwargs created!

This will impact keras_losses, keras_metrics, Search.set_reporter, Search.trainable, and mnist_example

glimr/glimr/search.py

Line 221 in cf1418d

if metrics is None:

https://github.com/PathologyDataScience/glimr/blob/cf1418db786eadf997b8e149d80b15def497d387/glimr/search.py#L324C40-L324C51

Addressed by PR #31