Use active layer and label for live wire

Summary:
Check for labelsetimage and use the correct pixel value

The tool has to check for the active layer and label to retrieve the correct pixel value.

Make sure the code of different tools is consistent

Test Plan: manual GUI testing

Reviewers: thomass, O1 MITK Reviewer Group I, floca, O3 MITK Reviewer Group II

Reviewed By: O1 MITK Reviewer Group I, floca, O3 MITK Reviewer Group II

Subscribers: floca, thomass, kalali

Maniphest Tasks: T27817

Differential Revision: https://phabricator.mitk.org/D447