[devel/pkg] Update the devel packaging

[devel/pkg] Update the devel packaging

Update the devel packaging to remove unnecessary headers.
- weight/var_grad headers are removed
- app_context and other graph, network related headers are removed. They
can be added once network/neural network headers are refactored for
custom models.
- manager and dynamic_training_optimization header is removed
- databuffer headers are commented. They will be updated once dataset
refactoring is done.

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