[nnc] Prepare the ACL backend for the future changes related to adding of the Tensor...

[nnc] Prepare the ACL backend for the future changes related to adding of the Tensor class in the ModelIR (#2933)

* Change the signature of `tensorName` and `genTensor` methods to accept `IODescriptor` instead of `Operation`.
* Use the `collectInputs` and `collectOutputs` methods of Graph class instead of collecting input and output operations manually in the ACL backend.
* Add `getInput` method to `Operation` class.
* Add uses of `getInput` method in the ACL backend.

Signed-off-by: Sergei Barannikov <s.barannikov@samsung.com>