git plugin - support pre-commit hooks

[jossef]

currently git plugin mechanism does not scan staging files, and allow committing them.

To add this support, we need to add a flag to the git plugin. I still don't know if the flag will be --staged or --include-staged, it depends on the implementation.

We implemented the git plugin based on the gitleaks implementation of reading the git log output. Need to see how they implemented their protect command and add it here.