Add common methods used by tox and CI script into dev tools

[praveenkuttappan]

Currently we have few duplicate methods in tox helper and common tasks that needsto be added into azure dev tools to have the implementation in one place. for e.g. finding whl from prebuilt directory, git helper functions etc.

[scbedd]

Addressed by #28345 !

We are consistently moving content from scripts/devops_tasks into the ci_tools module of azure-sdk-tools. This is an ongoing project but we have made a ton of progress here.