Implement sign function in NNCF tensor API

[mostafafaheem]

🚀 Feature request

The NNCF Tensor API provides a unified interface for tensor operations across different frameworks to support compression algorithms in a framework-agnostic manner. Currently, the element-wise sign operation (which returns an indication of the sign of a number) is missing from the abstraction layer.

Feature Use Case

This function is necessary for mathematical operations involving gradient manipulation or quantization schemes that depend on the sign of tensor elements.

Are you going to submit a PR?

• Yes I'd like to help by submitting a PR!