Respect workingDirectory on extracting git changed files

[Seitk]

The current filter-changed-files does not work with monorepo (see issue here)

The reason behind is that:

• jest test is usually under subfolder like packages/a, and the coverage will be generated along in the root directory of jest by default
• The file change detection based on git, which will be in the root of the git repo
• Such that the file path in test coverage file will never matches the file path in git compare

There are different ways to fix but the most intuitive one will be respecting the working directory we set in the GitHub action config when we get the changed file names from git compare