Add defaults to the docstrings for algorithms

[hanlint]

Fixes: #607 .

• All algorithms that have default arguments are not annotated as, for example:

alpha (float, optional): <description>. Default: 0.1

• Opportunistically cleans up some missing docstrings and type annotations here and there.

[dblalock]

Went thru the diff + all the pages under under composer.algorithms in the generated API reference and changes all LGTM, other than extra backticks in augmix.

I also noticed that public functions/modules in blurpool_layers, factorize_modules, factorize_core, and some stochastic_depth files didn't get "Default: whatever" strings, but maybe that was intentional limitation of this PR's scope.

[growlix]

Need to change one instance of RandAugment_image to randaugment_image (see comment) but otherwise lgtm!