[optimizer] Add optimizer wrapped

[optimizer] Add optimizer wrapped

Add optimizer wrapped which wraps the opitmizer and the learning rate
scheduler.
In order to be backward compatible, each optimizer must support setting
the learning rate, decay rate and decay steps, even for new optimizers.
To make this extensible without each optimizer storing this information
and merging with the learning rate schedulers, and not creating new
interfaces, optimizer wrapped is added.
Optimizer wraps around optimizer, and owns both the optimizer and
learning rate scheduler. If the properties of LR or decay are passed to
the optimizer, they are intercepted by the optimizer wrapped and passed
to the learning rate scheduler appropriately.

Signed-off-by: Parichay Kapoor <pk.kapoor@samsung.com>