[AIRFLOW-6351] security - ui - Add Cross Site Scripting defence

[tooptoop4]

Make sure you have checked all steps below.

Jira

• My PR addresses the following AIRFLOW-6351 issues and references them in the PR title. For example, "[AIRFLOW-6351] My Airflow PR"
  • https://issues.apache.org/jira/browse/AIRFLOW-6351
  • In case you are fixing a typo in the documentation you can prepend your commit with [AIRFLOW-6351], code changes always need a Jira issue.
  • In case you are proposing a fundamental code change, you need to create an Airflow Improvement Proposal (AIP).
  • In case you are adding a dependency, check if the license complies with the ASF 3rd Party License Policy.

Description

• Here are some details about my PR, including screenshots of any UI changes:

Tests

• My PR adds the following unit tests OR does not need testing for this extremely good reason:

Commits

• My commits all reference Jira issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters (not including Jira issue reference)
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Documentation

• In case of new functionality, my PR adds documentation that describes how to use it.
  • All the public functions and the classes in the PR contain docstrings that explain what it does
  • If you implement backwards incompatible changes, please leave a note in the Updating.md so we can assign it to a appropriate release

[turbaszek]

@tooptoop4 in Airflow we use amazing pre-commit framework that allow us to run all static analysis before committing. By using it you will eliminate need for refactoring your code and more importantly resources of our CI will be used more efficiently.
https://github.com/apache/airflow/blob/master/STATIC_CODE_CHECKS.rst#enabling-pre-commit-hooks

[tooptoop4]

@nuclearpinguin k, maybe docs need update as brew install xmllint does not work on Mac but brew install libxml2 works. Full steps I needed to get the checks:
(assuming brew and pip already installed)
pip install pre-commit
brew install gnu-getopt coreutils
echo 'export PATH="/usr/local/opt/gnu-getopt/bin:$PATH"' >> ~/.bash_profile;. ~/.bash_profile
brew cask install docker
run docker from Applications

[codecov-io]

Codecov Report

Merging #6913 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #6913   +/-   ##
=======================================
  Coverage   84.72%   84.72%           
=======================================
  Files         679      679           
  Lines       38505    38505           
=======================================
  Hits        32623    32623           
  Misses       5882     5882

Impacted Files	Coverage Δ
airflow/www/views.py	76.08% <100%> (ø)	⬆️

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