Move cosine LR scheduler with warmup from modules/ to training/

[ebsmothers]

Hopefully not a controversial suggestion? I think training is the more natural place for LR schedulers (unless there is some dependency issue I'm missing).

[krammnic]

It seem to me that this affects on recipes, docs and 1 test. Will open PR now. I don't sure, should we save it in modules for few versions due to backward capability reasons

[ebsmothers]

Thanks for creating the PR! I agree, let's keep the one in modules for now (but point everything to the version in training). Then add the deprecated flag saying that it will be removed in the 0.4 release and to use the one in training/ instead (example usage)

[krammnic]

Thanks for creating the PR! I agree, let's keep the one in modules for now (but point everything to the version in training). Then add the deprecated flag saying that it will be removed in the 0.4 release and to use the one in training/ instead (example usage)

Ok, will update PR then

[joecummings]

Closed by #1801