[nnc] ConstantOp, shape inference, model analyze, serialize, first artifact initial...

[nnc] ConstantOp, shape inference, model analyze, serialize, first artifact initial versions were implemented. (#2394)

New ConstantOp was added: at the moment it's used for input constant tensors like weights, etc.
Shape inference, model analyzing, etc, are working enough to be able to create the first artifact.

Signed-off-by: Andrew V. Tischenko <a.tischenko@partner.samsung.com>