pgAdmin 4 commit: Ensure Python escaping matched JS escaping and fix a

Ensure Python escaping matched JS escaping and fix a minor XSS issue in the Query Tool that required superuser access
totrigger. Fixes #4378 

Branch
------
master

Details
-------
https://git.postgresql.org/gitweb?p=pgadmin4.git;a=commitdiff;h=ebb5e3fe6542e721c6794bc7074252583350ca41
Author: Aditya Toshniwal <aditya.toshniwal@enterprisedb.com>

Modified Files
--------------
docs/en_US/release_notes_4_9.rst                 |  1 +
web/pgadmin/browser/utils.py                     | 25 ++++++++++++++++++++++++
web/pgadmin/tools/datagrid/__init__.py           |  4 +++-
web/pgadmin/tools/datagrid/static/js/datagrid.js |  2 +-
4 files changed, 30 insertions(+), 2 deletions(-)