pgAdmin 4 commit: popen() function strips the quotes from the arguments

popen() function strips the quotes from the arguments, so backup fails
for the schema name that needs quoting.

Code is changed to add escapers.

Fixes #4590

Branch
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master

Details
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https://git.postgresql.org/gitweb?p=pgadmin4.git;a=commitdiff;h=d056a94f0c30b44c4bab680a63f318de3226e958
Author: Aditya Toshniwal <aditya(dot)toshniwal(at)enterprisedb(dot)com>

Modified Files
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docs/en_US/release_notes_4_14.rst | 1 +
web/pgadmin/misc/bgprocess/__init__.py | 15 ++++++++++
web/pgadmin/misc/bgprocess/process_executor.py | 32 ++++++++++++++++++----
.../setup/tests/test_export_import_servers.py | 4 +--
web/pgadmin/tools/backup/__init__.py | 15 +++++++---
5 files changed, 55 insertions(+), 12 deletions(-)