pgAdmin 4 commit: Add full support and testsfor all PG server sideenco

Add full support and testsfor all PG server side encodings. Fixes #3992. Fixes #3982. Fixes #3911

Branch
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master

Details
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https://git.postgresql.org/gitweb?p=pgadmin4.git;a=commitdiff;h=849e34c2f763a9d084bd21840df6dde60c0a1b06
Author: Khushboo Vashi <khushboo.vashi@enterprisedb.com>

Modified Files
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.../tools/sqleditor/tests/test_encoding_charset.py | 187 +++++++++++++++++++--
web/pgadmin/utils/driver/psycopg2/connection.py    |  25 +--
web/pgadmin/utils/driver/psycopg2/encoding.py      |  64 +++++--
web/pgadmin/utils/driver/psycopg2/typecast.py      |  12 +-
web/pgadmin/utils/tests/test_encoding.py           | 154 +++++++++++++++--
5 files changed, 380 insertions(+), 62 deletions(-)