mv_machine_learning: code refactoring to input and output metadata classes

mv_machine_learning: code refactoring to input and output metadata classes

Did code refactoring to InputMetadata and OuputMetadata.

The biggest change of this patch is to delegate all requests
of various metadata relevant classes to InputMetadata and
OutputMetadata classes to mitigate Inference class dependency of
Metadata things.

In addition, it makes several classes declared in BoxInfo class to get out
, and changes class to struct in case that class functionality isn't needed.

And some cleanup and code sliding.

This is just one step for next code refactoring.

Change-Id: I92c4e2b2c77499246c56a237282c05262550301a
Signed-off-by: Inki Dae <inki.dae@samsung.com>