Script to print xsslint violations is missing

This was discovered as an existing issue while working on https://github.com/openedx/edx-platform/pull/35159

When xsslint detects a violation beyond the forgiven thresholds, rather than printing anything helpful, it fails with:

python scripts/xsslint/xss_linter.py \
--rule-totals \
--config=scripts.xsslint_config \
--thresholds=scripts/xsslint_thresholds.json
xsslint
FAILURE: XSSLinter Failed.
Too many violations total (65).
The limit is 64.
Too many python-concat-html violations (1).
The python-concat-html limit is 0.
run the following command to hone in on the problem:
./scripts/xss-commit-linter.sh -h
make: *** [Makefile:176: xsslint] Error 1

The script it tells you to run, ./scripts/xss-commit-linter.sh -h, does not exist.

We should provide the dev some way of seeing violations. Or, maybe we just print the violations every single time, like eslint does.

Start with scripts/xsslint/xss_linter.py and the xsslint target in Makefile, then reproduce the failure using the command shown in the issue. Check how the missing scripts/xss-commit-linter.sh is referenced and verify that the completed change exposes the XSSLint violations when thresholds are exceeded.