Tox and Zuul job for the bandit code scan in stx/gui

Setting up the bandit tool for the scanning of HIGH severity issues
in the python codes under Starlingx/gui folder.
Expecting this merge will enable zuul job for CI/CD of bandit scan.

Configuration files:
1. tox.ini for adding bandit environment and command.
2. test-requirements.txt for adding bandit version.
3. .zuul.yaml file for adding bandit job and configuring under
   check job to run code scan every time before code commit.

Test:
Run tox -e bandit command inside the fault folder to validate the
bandit scan and result.

Story: 2007541
Task: 39683
Depends-On: https://review.opendev.org/#/c/721294/

Change-Id: I155c9f894f8b1d701f2c75e3e892e6b83a35b11e
Signed-off-by: Sharath Kumar K <sharath.kumar@intel.com>

.zuul.yaml

@@ -3,6 +3,7 @@
     templates:
       - publish-stx-docs
       - stx-release-notes-jobs
+      - stx-bandit-jobs
     check:
       jobs:
         - openstack-tox-pep8

test-requirements.txt

@@ -26,3 +26,4 @@ testtools>=1.4.0 # MIT
 # This also needs xvfb library installed on your OS
 xvfbwrapper>=0.1.3 #license: MIT
 pyOpenSSL>=0.14
+bandit!=1.6.0,>=1.1.0,<2.0.0

tox.ini

@@ -98,3 +98,9 @@ basepython = python3
 envdir = {toxworkdir}/releasenotes
 deps = -r{toxinidir}/doc/requirements.txt
 commands = reno new {posargs}
+
+[testenv:bandit]
+basepython = python3
+description = Bandit code scan for *.py files under config folder
+deps = -r{toxinidir}/test-requirements.txt
+commands = bandit -r {toxinidir}/ -x '**/.tox/**,**/.eggs/**' -lll